Programs that call panic to crash after detecting a serious problem
may wish to use SetTraceback to force printing of all goroutines first.
Change-Id: Ib23ad9336f405485aabb642ca73f454a14c8baf3
Reviewed-on: https://go-review.googlesource.com/18043
Reviewed-by: Brad Fitzpatrick <bradfitz@golang.org>
Currently, if sigprof determines that the G is in user code (not cgo
or libcall code), it will only traceback the G stack if it can acquire
the stack barrier lock. However, it has no such restriction if the G
is in cgo or libcall code. Because cgo calls count as syscalls, stack
scanning and stack barrier installation can occur during a cgo call,
which means sigprof could attempt to traceback a G in a cgo call while
scanstack is installing stack barriers in that G's stack. As a result,
the following sequence of events can cause the sigprof traceback to
panic with "missed stack barrier":
1. M1: G1 performs a Cgo call (which, on Windows, is any system call,
which could explain why this is easier to reproduce on Windows).
2. M1: The Cgo call puts G1 into _Gsyscall state.
3. M2: GC starts a scan of G1's stack. It puts G1 in to _Gscansyscall
and acquires the stack barrier lock.
4. M3: A profiling signal comes in. On Windows this is a global
(though I don't think this matters), so the runtime stops M1 and
calls sigprof for G1.
5. M3: sigprof fails to acquire the stack barrier lock (because the
GC's stack scan holds it).
6. M3: sigprof observes that G1 is in a Cgo call, so it calls
gentraceback on G1 with its Cgo transition point.
7. M3: gentraceback on G1 grabs the currently empty g.stkbar slice.
8. M2: GC finishes scanning G1's stack and installing stack barriers.
9. M3: gentraceback encounters one of the just-installed stack
barriers and panics.
This commit fixes this by only allowing cgo tracebacks if sigprof can
acquire the stack barrier lock, just like in the regular user
traceback case.
For good measure, we put the same constraint on libcall tracebacks.
This case is probably already safe because, unlike cgo calls, libcalls
leave the G in _Grunning and prevent reaching a safe point, so
scanstack cannot run during a libcall. However, this also means that
sigprof will always acquire the stack barrier lock without contention,
so there's no cost to adding this constraint to libcall tracebacks.
Fixes#12528. For 1.5.3 (will require some backporting).
Change-Id: Ia5a4b8e3d66b23b02ffcd54c6315c81055c0cec2
Reviewed-on: https://go-review.googlesource.com/18023
Run-TryBot: Austin Clements <austin@google.com>
Reviewed-by: Russ Cox <rsc@golang.org>
Currently, setNextBarrierPC manipulates the stack barriers without
acquiring the stack barrier lock. This is mostly okay because
setNextBarrierPC also runs synchronously on the G and prevents safe
points, but this doesn't prevent a sigprof from occurring during a
setNextBarrierPC and performing a traceback.
Given that setNextBarrierPC simply sets one entry in the stack barrier
array, this is almost certainly safe in reality. However, given that
this depends on a subtle argument, which may not hold in the future,
and that setNextBarrierPC almost never happens, making it nowhere near
performance-critical, we can simply acquire the stack barrier lock and
be sure that the synchronization will work.
Updates #12528. For 1.5.3.
Change-Id: Ife696e10d969f190157eb1cbe762a2de2ebce079
Reviewed-on: https://go-review.googlesource.com/18022
Run-TryBot: Austin Clements <austin@google.com>
Reviewed-by: Russ Cox <rsc@golang.org>
I've already turned away one attempt to remove this field.
As the comment above the struct says, many tools know the layout.
The field cannot simply be removed.
It was one thing to remove the fields name, but the TODO should
not have been added.
Change-Id: If40eacf0eb35835082055e129e2b88333a0731b9
Reviewed-on: https://go-review.googlesource.com/17741
Reviewed-by: Brad Fitzpatrick <bradfitz@golang.org>
Reviewed-by: Ian Lance Taylor <iant@golang.org>
TestMemStats currently requires that NumGC != 0, but GC may
legitimately not have run (for example, if this test runs first, or
GOGC is set high, etc). Accept NumGC == 0 and instead sanity check
NumGC by making sure that all pause times after NumGC are 0.
Fixes#11989.
Change-Id: I4203859fbb83292d59a509f2eeb24d6033e7aabc
Reviewed-on: https://go-review.googlesource.com/17830
Run-TryBot: Austin Clements <austin@google.com>
TryBot-Result: Gobot Gobot <gobot@golang.org>
Reviewed-by: Mikio Hara <mikioh.mikioh@gmail.com>
This matches SIGEMT on other systems that use it (SIGEMT is not used
for most linux systems).
Change-Id: If394c06c9ed1cb3ea2564385a8edfbed8b5566d1
Reviewed-on: https://go-review.googlesource.com/17874
Run-TryBot: Ian Lance Taylor <iant@golang.org>
Reviewed-by: Minux Ma <minux@golang.org>
Currently, sysmon triggers a forced GC solely based on
memstats.last_gc. However, memstats.last_gc isn't updated until mark
termination, so once sysmon starts triggering forced GC, it will keep
triggering them until GC finishes. The first of these actually starts
a GC; the remainder up to the last print "GC forced", but gcStart
returns immediately because gcphase != _GCoff; then the last may start
another GC if the previous GC finishes (and sets last_gc) between
sysmon triggering it and gcStart checking the GC phase.
Fix this by expanding the condition for starting a forced GC to also
require that no GC is currently running. This, combined with the way
forcegchelper blocks until the GC cycle is started, ensures sysmon
only starts one GC when the time exceeds the forced GC threshold.
Fixes#13458.
Change-Id: Ie6cf841927f6085136be3f45259956cd5cf10d23
Reviewed-on: https://go-review.googlesource.com/17819
Run-TryBot: Austin Clements <austin@google.com>
TryBot-Result: Gobot Gobot <gobot@golang.org>
Reviewed-by: Russ Cox <rsc@golang.org>
The addition of stack barrier locking to copystack subsumes the
partial fix from commit bbd1a1c for SIGPROF during copystack. With the
stack barrier locking, this commit simplifies the rule in sigprof to:
the user stack can be traced only if sigprof can acquire the stack
barrier lock.
Updates #12932, #13362.
Change-Id: I1c1f80015053d0ac7761e9e0c7437c2aba26663f
Reviewed-on: https://go-review.googlesource.com/17192
Run-TryBot: Austin Clements <austin@google.com>
TryBot-Result: Gobot Gobot <gobot@golang.org>
Reviewed-by: Russ Cox <rsc@golang.org>
Currently, runtime/debug.SetGCPercent does not adjust the controller
trigger ratio. As a result, runtime reductions of GOGC don't take full
effect until after one more concurrent cycle has happened, which
adjusts the trigger ratio to account for the new gcpercent.
Fix this by lowering the trigger ratio if necessary in setGCPercent.
Change-Id: I4d23e0c58d91939b86ac60fa5d53ef91d0d89e0c
Reviewed-on: https://go-review.googlesource.com/17813
Run-TryBot: Austin Clements <austin@google.com>
TryBot-Result: Gobot Gobot <gobot@golang.org>
Reviewed-by: Russ Cox <rsc@golang.org>
Currently we drop worldsema and then print the gctrace. We did this so
that if stderr is a pipe or a blocked terminal, blocking on printing
the gctrace would not block another GC from starting. However, this is
a bit of a fool's errand because a blocked runtime print will block
the whole M/P, so after GOMAXPROCS GC cycles, the whole system will
freeze. Furthermore, now this is much less of an issue because
allocation will block indefinitely if it can't start a GC (whereas it
used to be that allocation could run away). Finally, this allows
another GC cycle to start while the previous cycle is printing the
gctrace, which leads to races on reading various statistics to print
them and the next GC cycle overwriting those statistics.
Fix this by moving the release of worldsema after the gctrace print.
Change-Id: I3d044ea0f77d80f3b4050af6b771e7912258662a
Reviewed-on: https://go-review.googlesource.com/17812
Run-TryBot: Austin Clements <austin@google.com>
Reviewed-by: Rick Hudson <rlh@golang.org>
TryBot-Result: Gobot Gobot <gobot@golang.org>
Reviewed-by: Russ Cox <rsc@golang.org>
Currently we reset the sweep stats just after gcMarkTermination starts
the world and releases worldsema. However, background sweeping can
start the moment we start the world and, in fact, pause sweeping can
start the moment we release worldsema (because another GC cycle can
start up), so these need to be cleared before starting the world.
Change-Id: I95701e3de6af76bb3fbf2ee65719985bf57d20b2
Reviewed-on: https://go-review.googlesource.com/17811
Run-TryBot: Austin Clements <austin@google.com>
TryBot-Result: Gobot Gobot <gobot@golang.org>
Reviewed-by: Russ Cox <rsc@golang.org>
Currently, we update memstats.heap_live from mcache.local_cachealloc
whenever we lock the heap (e.g., to obtain a fresh span or to release
an unused span). However, under the right circumstances,
local_cachealloc can accumulate allocations up to the size of
the *entire heap* without flushing them to heap_live. Specifically,
since span allocations from an mcentral don't lock the heap, if a
large number of pages are held in an mcentral and the application
continues to use and free objects of that size class (e.g., the
BinaryTree17 benchmark), local_cachealloc won't be flushed until the
mcentral runs out of spans.
This is a problem because, unlike many of the memory statistics that
are purely informative, heap_live is used to determine when the
garbage collector should start and how hard it should work.
This commit eliminates local_cachealloc, instead atomically updating
heap_live directly. To control contention, we do this only when
obtaining a span from an mcentral. Furthermore, we make heap_live
conservative: allocating a span assumes that all free slots in that
span will be used and accounts for these when the span is
allocated, *before* the objects themselves are. This is important
because 1) this triggers the GC earlier than necessary rather than
potentially too late and 2) this leads to a conservative GC rate
rather than a GC rate that is potentially too low.
Alternatively, we could have flushed local_cachealloc when it passed
some threshold, but this would require determining a threshold and
would cause heap_live to underestimate the true value rather than
overestimate.
Fixes#12199.
name old time/op new time/op delta
BinaryTree17-12 2.88s ± 4% 2.88s ± 1% ~ (p=0.470 n=19+19)
Fannkuch11-12 2.48s ± 1% 2.48s ± 1% ~ (p=0.243 n=16+19)
FmtFprintfEmpty-12 50.9ns ± 2% 50.7ns ± 1% ~ (p=0.238 n=15+14)
FmtFprintfString-12 175ns ± 1% 171ns ± 1% -2.48% (p=0.000 n=18+18)
FmtFprintfInt-12 159ns ± 1% 158ns ± 1% -0.78% (p=0.000 n=19+18)
FmtFprintfIntInt-12 270ns ± 1% 265ns ± 2% -1.67% (p=0.000 n=18+18)
FmtFprintfPrefixedInt-12 235ns ± 1% 234ns ± 0% ~ (p=0.362 n=18+19)
FmtFprintfFloat-12 309ns ± 1% 308ns ± 1% -0.41% (p=0.001 n=18+19)
FmtManyArgs-12 1.10µs ± 1% 1.08µs ± 0% -1.96% (p=0.000 n=19+18)
GobDecode-12 7.81ms ± 1% 7.80ms ± 1% ~ (p=0.425 n=18+19)
GobEncode-12 6.53ms ± 1% 6.53ms ± 1% ~ (p=0.817 n=19+19)
Gzip-12 312ms ± 1% 312ms ± 2% ~ (p=0.967 n=19+20)
Gunzip-12 42.0ms ± 1% 41.9ms ± 1% ~ (p=0.172 n=19+19)
HTTPClientServer-12 63.7µs ± 1% 63.8µs ± 1% ~ (p=0.639 n=19+19)
JSONEncode-12 16.4ms ± 1% 16.4ms ± 1% ~ (p=0.954 n=19+19)
JSONDecode-12 58.5ms ± 1% 57.8ms ± 1% -1.27% (p=0.000 n=18+19)
Mandelbrot200-12 3.86ms ± 1% 3.88ms ± 0% +0.44% (p=0.000 n=18+18)
GoParse-12 3.67ms ± 2% 3.66ms ± 1% -0.52% (p=0.001 n=18+19)
RegexpMatchEasy0_32-12 100ns ± 1% 100ns ± 0% ~ (p=0.257 n=19+18)
RegexpMatchEasy0_1K-12 347ns ± 1% 347ns ± 1% ~ (p=0.527 n=18+18)
RegexpMatchEasy1_32-12 83.7ns ± 2% 83.1ns ± 2% ~ (p=0.096 n=18+19)
RegexpMatchEasy1_1K-12 509ns ± 1% 505ns ± 1% -0.75% (p=0.000 n=18+19)
RegexpMatchMedium_32-12 130ns ± 2% 129ns ± 1% ~ (p=0.962 n=20+20)
RegexpMatchMedium_1K-12 39.5µs ± 2% 39.4µs ± 1% ~ (p=0.376 n=20+19)
RegexpMatchHard_32-12 2.04µs ± 0% 2.04µs ± 1% ~ (p=0.195 n=18+17)
RegexpMatchHard_1K-12 61.4µs ± 1% 61.4µs ± 1% ~ (p=0.885 n=19+19)
Revcomp-12 540ms ± 2% 542ms ± 4% ~ (p=0.552 n=19+17)
Template-12 69.6ms ± 1% 71.2ms ± 1% +2.39% (p=0.000 n=20+20)
TimeParse-12 357ns ± 1% 357ns ± 1% ~ (p=0.883 n=18+20)
TimeFormat-12 379ns ± 1% 362ns ± 1% -4.53% (p=0.000 n=18+19)
[Geo mean] 62.0µs 61.8µs -0.44%
name old time/op new time/op delta
XBenchGarbage-12 5.89ms ± 2% 5.81ms ± 2% -1.41% (p=0.000 n=19+18)
Change-Id: I96b31cca6ae77c30693a891cff3fe663fa2447a0
Reviewed-on: https://go-review.googlesource.com/17748
Run-TryBot: Austin Clements <austin@google.com>
TryBot-Result: Gobot Gobot <gobot@golang.org>
Reviewed-by: Russ Cox <rsc@golang.org>
deductSweepCredit expects the size in bytes of the span being
allocated, but mCentral_CacheSpan passes the size of a single object
in the span. As a result, we don't sweep enough on that call and when
mCentral_CacheSpan later calls reimburseSweepCredit, it's very likely
to underflow mheap_.spanBytesAlloc, which causes the next call to
deductSweepCredit to think it owes a huge number of pages and finish
off the whole sweep.
In addition to causing the occasional allocation that triggers the
full sweep to be potentially extremely expensive relative to other
allocations, this can indirectly slow down many other allocations.
deductSweepCredit uses sweepone to sweep spans, which returns
fully-unused spans to the heap, where these spans are freed and
coalesced with neighboring free spans. On the other hand, when
mCentral_CacheSpan sweeps a span, it does so with the intent to
immediately reuse that span and, as a result, will not return the span
to the heap even if it is fully unused. This saves on the cost of
locking the heap, finding a span, and initializing that span. For
example, before this change, with GOMAXPROCS=1 (or the background
sweeper disabled) BinaryTree17 returned roughly 220K spans to the heap
and allocated new spans from the heap roughly 232K times. After this
change, it returns 1.3K spans to the heap and allocates new spans from
the heap 39K times. (With background sweeping these numbers are
effectively unchanged because the background sweeper sweeps almost all
of the spans with sweepone; however, parallel sweeping saves more than
the cost of allocating spans from the heap.)
Fixes#13535.
Fixes#13589.
name old time/op new time/op delta
BinaryTree17-12 3.03s ± 1% 2.86s ± 4% -5.61% (p=0.000 n=18+20)
Fannkuch11-12 2.48s ± 1% 2.49s ± 1% ~ (p=0.060 n=17+20)
FmtFprintfEmpty-12 50.7ns ± 1% 50.9ns ± 1% +0.43% (p=0.025 n=15+16)
FmtFprintfString-12 174ns ± 2% 174ns ± 2% ~ (p=0.539 n=19+20)
FmtFprintfInt-12 158ns ± 1% 158ns ± 1% ~ (p=0.300 n=18+20)
FmtFprintfIntInt-12 269ns ± 2% 269ns ± 2% ~ (p=0.784 n=20+18)
FmtFprintfPrefixedInt-12 233ns ± 1% 234ns ± 1% ~ (p=0.389 n=18+18)
FmtFprintfFloat-12 309ns ± 1% 310ns ± 1% +0.25% (p=0.048 n=18+18)
FmtManyArgs-12 1.10µs ± 1% 1.10µs ± 1% ~ (p=0.259 n=18+19)
GobDecode-12 7.81ms ± 1% 7.72ms ± 1% -1.17% (p=0.000 n=19+19)
GobEncode-12 6.56ms ± 0% 6.55ms ± 1% ~ (p=0.433 n=17+19)
Gzip-12 318ms ± 2% 317ms ± 1% ~ (p=0.578 n=19+18)
Gunzip-12 42.1ms ± 2% 42.0ms ± 0% -0.45% (p=0.007 n=18+16)
HTTPClientServer-12 63.9µs ± 1% 64.0µs ± 1% ~ (p=0.146 n=17+19)
JSONEncode-12 16.4ms ± 1% 16.4ms ± 1% ~ (p=0.271 n=19+19)
JSONDecode-12 58.1ms ± 1% 58.0ms ± 1% ~ (p=0.152 n=18+18)
Mandelbrot200-12 3.85ms ± 0% 3.85ms ± 0% ~ (p=0.126 n=19+18)
GoParse-12 3.71ms ± 1% 3.64ms ± 1% -1.86% (p=0.000 n=20+18)
RegexpMatchEasy0_32-12 100ns ± 2% 100ns ± 1% ~ (p=0.588 n=20+20)
RegexpMatchEasy0_1K-12 346ns ± 1% 347ns ± 1% +0.27% (p=0.014 n=17+20)
RegexpMatchEasy1_32-12 82.9ns ± 3% 83.5ns ± 3% ~ (p=0.096 n=19+20)
RegexpMatchEasy1_1K-12 506ns ± 1% 506ns ± 1% ~ (p=0.530 n=19+19)
RegexpMatchMedium_32-12 129ns ± 2% 129ns ± 1% ~ (p=0.566 n=20+19)
RegexpMatchMedium_1K-12 39.4µs ± 1% 39.4µs ± 1% ~ (p=0.713 n=19+20)
RegexpMatchHard_32-12 2.05µs ± 1% 2.06µs ± 1% +0.36% (p=0.008 n=18+20)
RegexpMatchHard_1K-12 61.6µs ± 1% 61.7µs ± 1% ~ (p=0.286 n=19+20)
Revcomp-12 538ms ± 1% 541ms ± 2% ~ (p=0.081 n=18+19)
Template-12 71.5ms ± 2% 71.6ms ± 1% ~ (p=0.513 n=20+19)
TimeParse-12 357ns ± 1% 357ns ± 1% ~ (p=0.935 n=19+18)
TimeFormat-12 352ns ± 1% 352ns ± 1% ~ (p=0.293 n=19+20)
[Geo mean] 62.0µs 61.9µs -0.21%
name old time/op new time/op delta
XBenchGarbage-12 5.83ms ± 2% 5.86ms ± 3% ~ (p=0.247 n=19+20)
Change-Id: I790bb530adace27ccf25d372f24a11954b88443c
Reviewed-on: https://go-review.googlesource.com/17745
Run-TryBot: Austin Clements <austin@google.com>
TryBot-Result: Gobot Gobot <gobot@golang.org>
Reviewed-by: Rick Hudson <rlh@golang.org>
Reviewed-by: Russ Cox <rsc@golang.org>
Analogous to https://go-review.googlesource.com/#/c/8457/ this
code synthesizes an set of program arguments for Android on the
arm64 architecture.
Change-Id: I851958b4b0944ec79d7a1426a3bb2cfc31746797
Reviewed-on: https://go-review.googlesource.com/17782
Reviewed-by: David Crawshaw <crawshaw@golang.org>
Run-TryBot: David Crawshaw <crawshaw@golang.org>
TryBot-Result: Gobot Gobot <gobot@golang.org>
To prevent races with the garbage collector, stack spans cannot be
reused as heap spans during a GC. We deal with this by caching stack
spans during GC and releasing them at the end of mark termination.
However, while our cache lets us reuse small stack spans, currently
large stack spans are *not* reused. This can cause significant memory
growth in programs that allocate large stacks rapidly, but grow the
heap slowly (such as in issue #13552).
Fix this by adding logic to reuse large stack spans for other stacks.
Fixes#11466.
Fixes#13552. Without this change, the program in this issue creeps to
over 1GB of memory over the course of a few hours. With this change,
it stays rock solid at around 30MB.
Change-Id: If8b2d85464aa80c96230a1990715e39aa803904f
Reviewed-on: https://go-review.googlesource.com/17814
Reviewed-by: Keith Randall <khr@golang.org>
Currently we wake up new worker threads whenever we pass
through the scheduler with nmspinning==0. This leads to
lots of unnecessary thread wake ups.
Instead let only spinning threads wake up new spinning threads.
For the following program:
package main
import "runtime"
func main() {
for i := 0; i < 1e7; i++ {
runtime.Gosched()
}
}
Before:
$ time ./test
real 0m4.278s
user 0m7.634s
sys 0m1.423s
$ strace -c ./test
% time seconds usecs/call calls errors syscall
99.93 9.314936 3 2685009 17536 futex
After:
$ time ./test
real 0m1.200s
user 0m1.181s
sys 0m0.024s
$ strace -c ./test
% time seconds usecs/call calls errors syscall
3.11 0.000049 25 2 futex
Fixes#13527
Change-Id: Ia1f5bf8a896dcc25d8b04beb1f4317aa9ff16f74
Reviewed-on: https://go-review.googlesource.com/17540
Reviewed-by: Austin Clements <austin@google.com>
Run-TryBot: Dmitry Vyukov <dvyukov@google.com>
TryBot-Result: Gobot Gobot <gobot@golang.org>
debug.schedtrace is an int32. Convert it to int64 before
multiplying with constant 1000000. Otherwise, schedtrace
values more than 2147 result in int32 overflow causing
incorrect delays between traces.
Change-Id: I064e8d7b432c1e892a705ee1f31a2e8cdd2c3ea3
Reviewed-on: https://go-review.googlesource.com/17712
Reviewed-by: Austin Clements <austin@google.com>
Run-TryBot: Ian Lance Taylor <iant@golang.org>
If reports like #13062 are really concurrent misuse of maps,
we can detect that, at least some of the time, with a cheap check.
There is an extra pair of memory writes for writing to a map,
but to the same cache line as h.count, which is often being modified anyway,
and there is an extra memory read for reading from a map,
but to the same cache line as h.count, which is always being read anyway.
So the check should be basically invisible and may help reduce the
number of "mysterious runtime crash due to map misuse" reports.
Change-Id: I0e71b0d92eaa3b7bef48bf41b0f5ab790092487e
Reviewed-on: https://go-review.googlesource.com/17501
Reviewed-by: Keith Randall <khr@golang.org>
Reviewed-by: Brad Fitzpatrick <bradfitz@golang.org>
Reviewed-by: Austin Clements <austin@google.com>
(sig is unsigned, so sig-1 >= 0 is always true.)
Fixes#11281.
Change-Id: I4b9d784da6e3cc80816f2d2f7228d5d8a237e2d5
Reviewed-on: https://go-review.googlesource.com/17457
Reviewed-by: Ian Lance Taylor <iant@golang.org>
Run-TryBot: Brad Fitzpatrick <bradfitz@golang.org>
When run with "ulimit -s unlimited", the misc/cgo/test test binary
finds a stack size of 0x3000 returned by getcontext, causing the
runtime to try to stay within those bounds and then fault when
called back in the test after 64 kB has been used by C.
I suspect that Solaris is doing something clever like reporting the
current stack size and growing the stack as faults happen.
On all the other systems, getcontext reports the maximum stack size.
And when the ulimit is not unlimited, even Solaris reports the
maximum stack size.
Work around this by assuming that any stack on Solaris must be at least 1 MB.
Fixes#12210.
Change-Id: I0a6ed0afb8a8f50aa1b2486f32b4ae470ab47dbf
Reviewed-on: https://go-review.googlesource.com/17452
Reviewed-by: Ian Lance Taylor <iant@golang.org>
stackBarrier on amd64 sanity checks that it's unwinding the correct
entry in the stack barrier array. However, this check is wrong in two
ways that make it unlikely to catch anything, right or wrong:
1) It checks that savedLRPtr == SP, but, in fact, it should be that
savedLRPtr+8 == SP because the RET that returned to stackBarrier
popped the saved LR. However, we didn't notice this check was wrong
because,
2) the sense of the conditional branch is also wrong.
Fix both of these.
Change-Id: I38ba1f652b0168b5b2c11b81637656241262af7c
Reviewed-on: https://go-review.googlesource.com/17039
Reviewed-by: Russ Cox <rsc@golang.org>
On android, runtime.tls_g is a normal variable.
TLS offset is computed in x_cgo_inittls.
Change-Id: I18bc9a736d5fb2a89d0f798956c754e3c10d10e2
Reviewed-on: https://go-review.googlesource.com/17246
Reviewed-by: David Crawshaw <crawshaw@golang.org>
On android, runtime.tls_g is a normal variable.
TLS offset is computed in x_cgo_inittls.
Change-Id: I64cfd3543040776dcdf73cad8dba54fc6aaf6f35
Reviewed-on: https://go-review.googlesource.com/17245
Reviewed-by: David Crawshaw <crawshaw@golang.org>
The ppc64le shared library ABI demands that r12 is set to a function's global
entrypoint before jumping to the global entrypoint. Not doing so means that
handling signals that usually panic actually crashes (and so, e.g. can't be
recovered). Fixes several failures of "cd test; go run run.go -linkshared".
Change-Id: Ia4d0da4c13efda68340d38c045a52b37c2f90796
Reviewed-on: https://go-review.googlesource.com/17280
Reviewed-by: Ian Lance Taylor <iant@golang.org>
We need a runtime check because the original issue is encountered
when running cross compiled windows program from linux. It's better
to give a meaningful crash message earlier than to segfault later.
The added test should not impose any measurable overhead to Go
programs.
For #12415.
Change-Id: Ib4a24ef560c09c0585b351d62eefd157b6b7f04c
Reviewed-on: https://go-review.googlesource.com/14207
Reviewed-by: Keith Randall <khr@golang.org>
Run-TryBot: Minux Ma <minux@golang.org>
TryBot-Result: Gobot Gobot <gobot@golang.org>
Write barriers in gcFlushBgCredit lead to very subtle bugs because it
executes after the getfull barrier. I tracked some bugs of this form
down before go:nowritebarrierrec was implemented. Ensure that they
don't reappear by making gcFlushBgCredit go:nowritebarrierrec.
Change-Id: Ia5ca2dc59e6268bce8d8b4c87055bd0f6e19bed2
Reviewed-on: https://go-review.googlesource.com/17052
Reviewed-by: Russ Cox <rsc@golang.org>
sighandler may run during STW, so write barriers are not allowed.
Change-Id: Icdf46be10ea296fd87e73ab56ebb718c5d3c97ac
Reviewed-on: https://go-review.googlesource.com/17007
Reviewed-by: Russ Cox <rsc@golang.org>
Replace the cross platform but unsafe [4]uintptr type with a OS
specific type, sigset. Most OSes already define sigset, and this
change defines a suitable sigset for the OSes that don't (darwin,
openbsd). The OSes that don't use m.sigmask (windows, plan9, nacl)
now defines sigset as the empty type, struct{}.
The gain is strongly typed access to m.sigmask, saving a dynamic
size sanity check and unsafe.Pointer casting. Also, some storage is
saved for each M, since [4]uinptr was conservative for most OSes.
The cost is that OSes that don't need m.sigmask has to define sigset.
completes ./all.bash with GOOS linux, on amd64
completes ./make.bash with GOOSes openbsd, android, plan9, windows,
darwin, solaris, netbsd, freebsd, dragonfly, all amd64.
With GOOS=nacl ./make.bash failed with a seemingly unrelated error.
[Replay of CL 16942 by Elias Naur.]
Change-Id: I98f144d626033ae5318576115ed635415ac71b2c
Reviewed-on: https://go-review.googlesource.com/17033
Reviewed-by: Brad Fitzpatrick <bradfitz@golang.org>
Reviewed-by: Ian Lance Taylor <iant@golang.org>
Run-TryBot: Russ Cox <rsc@golang.org>
These tests were failing on one of the versions of cl/9345
("runtime: simplify buffered channels").
Change-Id: I920ffcd28de428bcb7c2d5a300068644260e1017
Reviewed-on: https://go-review.googlesource.com/16416
Reviewed-by: Keith Randall <khr@golang.org>
Run-TryBot: Dmitry Vyukov <dvyukov@google.com>
TryBot-Result: Gobot Gobot <gobot@golang.org>
Fixes#11959Fixes#12035
Skip the CallbackGC test on linux/arm. This test takes between 30 and 60
seconds to run by itself, and is run 4 times over the course of ./run.bash
(once during the runtime test, three times more later in the build).
Change-Id: I4e7d3046031cd8c08f39634bdd91da6e00054caf
Reviewed-on: https://go-review.googlesource.com/14485
Reviewed-by: Russ Cox <rsc@golang.org>
Original code is mistakenly panics on VirtualAlloc failure - we want
it to go looking for smaller memory region that VirtualAlloc will
succeed to allocate. Also return immediately if VirtualAlloc succeeds.
See rsc comment on issue #12587 for details.
I still don't have a test for this. So I can only hope that this
Fixes#12587
Change-Id: I052068ec627fdcb466c94ae997ad112016f734b7
Reviewed-on: https://go-review.googlesource.com/17169
Reviewed-by: Russ Cox <rsc@golang.org>
These are methods that are "obviously" going to get inlined -- until you build
with -l, when they can trigger a stack split at a bad time.
Fixes#11482
Change-Id: Ia065c385978a2e7fe9f587811991d088c4d68325
Reviewed-on: https://go-review.googlesource.com/17165
Run-TryBot: Michael Hudson-Doyle <michael.hudson@canonical.com>
TryBot-Result: Gobot Gobot <gobot@golang.org>
Reviewed-by: Russ Cox <rsc@golang.org>
Commit bbd1a1c prevented SIGPROF from scanning stacks that were being
copied, but it didn't prevent a stack copy (specifically a stack
shrink) from happening while SIGPROF is scanning the stack. As a
result, a stack copy may adjust stack barriers while SIGPROF is in the
middle of scanning a stack, causing SIGPROF to panic when it detects
an inconsistent stack barrier.
Fix this by taking the stack barrier lock while adjusting the stack.
In addition to preventing SIGPROF from scanning this stack, this will
block until any in-progress SIGPROF is done scanning the stack.
For 1.5.2.
Fixes#13362.
Updates #12932.
Change-Id: I422219c363054410dfa56381f7b917e04690e5dd
Reviewed-on: https://go-review.googlesource.com/17191
Run-TryBot: Austin Clements <austin@google.com>
Reviewed-by: Russ Cox <rsc@golang.org>
Run-TryBot: Russ Cox <rsc@golang.org>
TryBot-Result: Gobot Gobot <gobot@golang.org>
Calling timeBeginPeriod changes Windows global timer resolution
from 15ms to 1ms. This used to improve Go runtime scheduler
performance, but not anymore. Thanks to @aclements, scheduler now
behaves the same way if we call timeBeginPeriod or not.
Remove call to timeBeginPeriod, since it is machine global
resource, and there are downsides of using low timer resolution.
See issue #8687 for details.
Fixes#8687
Change-Id: Ib7e41aa4a81861b62a900e0e62776c9ef19bfb73
Reviewed-on: https://go-review.googlesource.com/17164
Reviewed-by: Austin Clements <austin@google.com>
Reviewed-by: Brad Fitzpatrick <bradfitz@golang.org>
Reviewed-by: Yasuhiro MATSUMOTO <mattn.jp@gmail.com>
Run-TryBot: Alex Brainman <alex.brainman@gmail.com>
This improves the documentation comment on gcMarkDone, replaces a
recursive call with a simple goto, and disables preemption before
stopping the world in accordance with the documentation comment on
stopTheWorldWithSema.
Updates #13363, but, sadly, doesn't fix it.
Change-Id: I6cb2a5836b35685bf82f7b1ce7e48a7625906656
Reviewed-on: https://go-review.googlesource.com/17149
Reviewed-by: Rick Hudson <rlh@golang.org>
Run-TryBot: Austin Clements <austin@google.com>
TryBot-Result: Gobot Gobot <gobot@golang.org>
This improves stack barrier debugging messages in various ways:
1) Rather than printing only the remaining stack barriers (of which
there may be none, which isn't very useful), print all of the G's
stack barriers with a marker at the position the stack itself has
unwound to and a marker at the problematic stack barrier (where
applicable).
2) Rather than crashing if we encounter a stack barrier when there are
no more stkbar entries, print the same debug message we would if we
had encountered a stack barrier at an unexpected location.
Hopefully this will help with debugging #12528.
Change-Id: I2e6fe6a778e0d36dd8ef30afd4c33d5d94731262
Reviewed-on: https://go-review.googlesource.com/17147
Reviewed-by: Rick Hudson <rlh@golang.org>
Reviewed-by: Russ Cox <rsc@golang.org>
The stack barrier locking functions use a simple cas lock because they
need to support trylock, but currently don't increment g.m.locks. This
is okay right now because they always run on the system stack or the
signal stack and are hence non-preemtible, but this could lead to
difficult-to-reproduce deadlocks if these conditions change in the
future.
Make these functions more robust by incrementing g.m.locks and making
them nosplit to enforce non-preemtibility.
Change-Id: I73d60a35bd2ad2d81c73aeb20dbd37665730eb1b
Reviewed-on: https://go-review.googlesource.com/17058
Run-TryBot: Austin Clements <austin@google.com>
TryBot-Result: Gobot Gobot <gobot@golang.org>
Reviewed-by: Ingo Oeser <nightlyone@googlemail.com>
Reviewed-by: Russ Cox <rsc@golang.org>
This test depends on GODEBUG=gcstackbarrierall, which doesn't work on
ppc64.
Updates #13334.
Change-Id: Ie554117b783c4e999387f97dd660484488499d85
Reviewed-on: https://go-review.googlesource.com/17120
Run-TryBot: Austin Clements <austin@google.com>
Reviewed-by: Russ Cox <rsc@golang.org>
During a crash showing goroutine stacks of all threads
(with GOTRACEBACK=crash), it can be that f == nil.
Only happens on Solaris; not sure why.
Change-Id: Iee2c394a0cf19fa0a24f6befbc70776b9e42d25a
Reviewed-on: https://go-review.googlesource.com/17110
Reviewed-by: Austin Clements <austin@google.com>
The nosplit stack is now much bigger, so we can afford to allocate
libcall on stack.
Fix asmsysvicall6 to not update errno if g == nil.
These two fixes TestCgoCallbackGC on solaris, which used to stuck
in a loop.
Change-Id: Id1b13be992dae9f059aa3d47ffffd37785300933
Reviewed-on: https://go-review.googlesource.com/17076
Run-TryBot: Minux Ma <minux@golang.org>
Reviewed-by: Ian Lance Taylor <iant@golang.org>
TryBot-Result: Gobot Gobot <gobot@golang.org>
Solaris needs to make system calls without a g,
and Solaris uses asmcgocall to make system calls.
I know, I know.
I hope this makes CL 16915, fixing #12277, work on Solaris.
Change-Id: If988dfd37f418b302da9c7096f598e5113ecea87
Reviewed-on: https://go-review.googlesource.com/17072
Reviewed-by: Ian Lance Taylor <iant@golang.org>
Reviewed-by: Aram Hăvărneanu <aram@mgk.ro>
Run-TryBot: Russ Cox <rsc@golang.org>
sysmon runs without a P. This means it can't interact with the garbage
collector, so write barriers not allowed in anything that sysmon does.
Fixes#10600.
Change-Id: I9de1283900dadee4f72e2ebfc8787123e382ae88
Reviewed-on: https://go-review.googlesource.com/17006
Run-TryBot: Austin Clements <austin@google.com>
Reviewed-by: Dmitry Vyukov <dvyukov@google.com>
TryBot-Result: Gobot Gobot <gobot@golang.org>
allocm is a very unusual function: it is specifically designed to
allocate in contexts where m.p is nil by temporarily taking over a P.
Since allocm is used in many contexts where it would make sense to use
nowritebarrierrec, this commit teaches the nowritebarrierrec analysis
to stop at allocm.
Updates #10600.
Change-Id: I8499629461d4fe25712d861720dfe438df7ada9b
Reviewed-on: https://go-review.googlesource.com/17005
Reviewed-by: Russ Cox <rsc@golang.org>
gentraceback is used in many contexts where write barriers are
disallowed. This currently works because the only write barrier is in
assigning frame.argmap in setArgInfo and in practice frame is always
on the stack, so this write barrier is a no-op.
However, we can easily eliminate this write barrier, which will let us
statically disallow write barriers (using go:nowritebarrierrec
annotations) in many more situations. As a bonus, this makes the code
a little more idiomatic.
Updates #10600.
Change-Id: I45ba5cece83697ff79f8537ee6e43eadf1c18c6d
Reviewed-on: https://go-review.googlesource.com/17003
Run-TryBot: Austin Clements <austin@google.com>
TryBot-Result: Gobot Gobot <gobot@golang.org>
Reviewed-by: Dmitry Vyukov <dvyukov@google.com>
The assumption is that there are no nested function calls in complex expressions.
For the most part that assumption is true. It wasn't for these calls inserted during walk.
Fix that.
I looked through all the calls to mkcall in walk and these were the only cases
that emitted calls, that could be part of larger expressions (like not delete),
and that were not already handled.
Fixes#12225.
Change-Id: Iad380683fe2e054d480e7ae4e8faf1078cdd744c
Reviewed-on: https://go-review.googlesource.com/17034
Reviewed-by: Ian Lance Taylor <iant@golang.org>
This adds a test that runs CPU profiling with a high load of stack
barriers and stack barrier insertion/removal operations and checks
that both 1) the runtime doesn't crash and 2) stackBarrier itself
never appears in a profile. Prior to the fix for gentraceback starting
in the middle of stackBarrier, condition 2 often failed.
Change-Id: Ic28860448859029779844c4bf3bb28ca84611e2c
Reviewed-on: https://go-review.googlesource.com/17037
Reviewed-by: Russ Cox <rsc@golang.org>
Run-TryBot: Austin Clements <austin@google.com>
TryBot-Result: Gobot Gobot <gobot@golang.org>
A sigprof during stack barrier insertion or removal can crash if it
detects an inconsistency between the stkbar array and the stack
itself. Currently we protect against this when scanning another G's
stack using stackLock, but we don't protect against it when unwinding
stack barriers for a recover or a memmove to the stack.
This commit cleans up and improves the stack locking code. It
abstracts out the lock and unlock operations. It uses the lock
consistently everywhere we perform stack operations, and pushes the
lock/unlock down closer to where the stack barrier operations happen
to make it more obvious what it's protecting. Finally, it modifies
sigprof so that instead of spinning until it acquires the lock, it
simply doesn't perform a traceback if it can't acquire it. This is
necessary to prevent self-deadlock.
Updates #11863, which introduced stackLock to fix some of these
issues, but didn't go far enough.
Updates #12528.
Change-Id: I9d1fa88ae3744d31ba91500c96c6988ce1a3a349
Reviewed-on: https://go-review.googlesource.com/17036
Reviewed-by: Russ Cox <rsc@golang.org>
Run-TryBot: Austin Clements <austin@google.com>
TryBot-Result: Gobot Gobot <gobot@golang.org>
Currently, if a profiling signal happens in the middle of
stackBarrier, gentraceback may see inconsistencies between stkbar and
the barriers on the stack and it will certainly get the wrong return
PC for stackBarrier. In most cases, the return PC won't be a PC at all
and this will immediately abort the traceback (which is considered
okay for a sigprof), but if it happens to be a valid PC this may sent
gentraceback down a rabbit hole.
Fix this by detecting when the gentraceback starts in stackBarrier and
simulating the completion of the barrier to get the correct initial
frame.
Change-Id: Ib11f705ac9194925f63fe5dfbfc84013a38333e6
Reviewed-on: https://go-review.googlesource.com/17035
Reviewed-by: Russ Cox <rsc@golang.org>
Run-TryBot: Austin Clements <austin@google.com>
TryBot-Result: Gobot Gobot <gobot@golang.org>
Cgo-created threads transition between having associated Go g's and m's and not.
A signal arriving during the transition could think it was safe and appropriate to
run Go signal handlers when it was in fact not.
Avoid the race by masking all signals during the transition.
Fixes#12277.
Change-Id: Ie9711bc1d098391d58362492197a7e0f5b497d14
Reviewed-on: https://go-review.googlesource.com/16915
Reviewed-by: Ian Lance Taylor <iant@golang.org>
Run-TryBot: Russ Cox <rsc@golang.org>
TryBot-Result: Gobot Gobot <gobot@golang.org>
Mostly by avoiding CX entirely, sometimes by reloading it.
I also vetted the assembly in other packages, it's all fine.
Change-Id: I50059669aaaa04efa303cf22ac228f9d14d83db0
Reviewed-on: https://go-review.googlesource.com/16386
Reviewed-by: Ian Lance Taylor <iant@golang.org>
Replace the cross platform but unsafe [4]uintptr type with a OS
specific type, sigset. Most OSes already define sigset, and this
change defines a suitable sigset for the OSes that don't (darwin,
openbsd). The OSes that don't use m.sigmask (windows, plan9, nacl)
now defines sigset as the empty type, struct{}.
The gain is strongly typed access to m.sigmask, saving a dynamic
size sanity check and unsafe.Pointer casting. Also, some storage is
saved for each M, since [4]uinptr was conservative for most OSes.
The cost is that OSes that don't need m.sigmask has to define sigset.
completes ./all.bash with GOOS linux, on amd64
completes ./make.bash with GOOSes openbsd, android, plan9, windows,
darwin, solaris, netbsd, freebsd, dragonfly, all amd64.
With GOOS=nacl ./make.bash failed with a seemingly unrelated error.
R=go1.7
Change-Id: Ib460379f063eb83d393e1c5efe7333a643c1595e
Reviewed-on: https://go-review.googlesource.com/16942
Reviewed-by: Ian Lance Taylor <iant@golang.org>
Run-TryBot: Ian Lance Taylor <iant@golang.org>
TryBot-Result: Gobot Gobot <gobot@golang.org>
golang.org/cl/16796 broke android/386 by assuming behaviour specific to glibc's
dynamic linker. Copy bionic by using int $0x80 to invoke syscalls on
android/386 as the old alternative (CALL *runtime_vdso(SB)) cannot be compiled
without text relocations, which we want to get rid of on android.
Also remove "CALL *runtime_vdso(SB)" variant from the syscall package.
Change-Id: I6c01849f8dcbd073d000ddc8f13948a836b8b261
Reviewed-on: https://go-review.googlesource.com/16996
TryBot-Result: Gobot Gobot <gobot@golang.org>
Reviewed-by: David Crawshaw <crawshaw@golang.org>
Reviewed-by: Hyang-Ah Hana Kim <hyangah@gmail.com>
Not all tests passing yet, but a good chunk are.
Change-Id: I5daebaeabf3aecb380674ece8830a86751a8d139
Reviewed-on: https://go-review.googlesource.com/16458
Reviewed-by: Rahul Chaudhry <rahulchaudhry@google.com>
Reviewed-by: David Crawshaw <crawshaw@golang.org>
Currently, if an allocation is large enough that arena_end + size
overflows (which is not hard to do on 32-bit), we go ahead and call
sysReserve with the impossible base and length and depend on this to
either directly fail because the kernel can't possibly fulfill the
requested mapping (causing mheap.sysAlloc to return nil) or to succeed
with a mapping at some other address which will then be rejected as
outside the arena.
In order to make this less subtle, less dependent on the kernel
getting all of this right, and to eliminate the hopeless system call,
add an explicit overflow check.
Updates #13143. This real issue has been fixed by 0de59c2, but this is
a belt-and-suspenders improvement on top of that. It was uncovered by
my symbolic modeling of that bug.
Change-Id: I85fa868a33286fdcc23cdd7cdf86b19abf1cb2d1
Reviewed-on: https://go-review.googlesource.com/16961
Run-TryBot: Austin Clements <austin@google.com>
TryBot-Result: Gobot Gobot <gobot@golang.org>
Reviewed-by: Ian Lance Taylor <iant@golang.org>
mcache.tiny is in non-GC'd memory, but points to heap memory. As a
result, there may or may not be write barriers when writing to
mcache.tiny. Make it clearer that funny things are going on by making
mcache.tiny a uintptr instead of an unsafe.Pointer.
Change-Id: I732a5b7ea17162f196a9155154bbaff8d4d00eac
Reviewed-on: https://go-review.googlesource.com/16963
Run-TryBot: Austin Clements <austin@google.com>
Reviewed-by: Russ Cox <rsc@golang.org>
Reviewed-by: Keith Randall <khr@golang.org>
TryBot-Result: Gobot Gobot <gobot@golang.org>
The tiny alloc cache is maintained in a pointer from non-GC'd memory
(mcache) to heap memory and hence must be handled carefully.
Currently we clear the tiny alloc cache during sweep termination and,
if it is assigned to a non-nil value during concurrent marking, we
depend on a write barrier to keep the new value alive. However, while
the compiler currently always generates this write barrier, we're
treading on thin ice because write barriers may not happen for writes
to non-heap memory (e.g., typedmemmove). Without this lucky write
barrier, the GC may free a current tiny block while it's still
reachable by the tiny allocator, leading to later memory corruption.
Change this code so that, rather than depending on the write barrier,
we simply clear the tiny cache during mark termination when we're
clearing all of the other mcaches. If the current tiny block is
reachable from regular pointers, it will be retained; if it isn't
reachable from regular pointers, it may be freed, but that's okay
because there won't be any pointers in non-GC'd memory to it.
Change-Id: I8230980d8612c35c2997b9705641a1f9f865f879
Reviewed-on: https://go-review.googlesource.com/16962
Run-TryBot: Austin Clements <austin@google.com>
Reviewed-by: Russ Cox <rsc@golang.org>
Reviewed-by: Keith Randall <khr@golang.org>
TryBot-Result: Gobot Gobot <gobot@golang.org>
If you set GODEBUG=cgocheck=2 the runtime package will use the write
barrier to detect cases where a Go program writes a Go pointer into
non-Go memory. In conjunction with the existing cgo checks, and the
not-yet-implemented cgo check for exported functions, this should
reliably detect all cases (that do not import the unsafe package) in
which a Go pointer is incorrectly shared with C code. This check is
optional because it turns on the write barrier at all times, which is
known to be expensive.
Update #12416.
Change-Id: I549d8b2956daa76eac853928e9280e615d6365f4
Reviewed-on: https://go-review.googlesource.com/16899
Reviewed-by: Russ Cox <rsc@golang.org>
In mheap.sysAlloc, if an allocation at arena_used would exceed
arena_end (but wouldn't yet push us past arena_start+_MaxArean32), it
trie to extend the arena reservation by another 256 MB. It extends the
arena by calling sysReserve, which, on 32-bit, calls mmap without
MAP_FIXED, which means the address is just a hint and the kernel can
put the mapping wherever it wants. In particular, mmap may choose an
address below arena_start (the kernel also chose arena_start, so there
could be lots of space below it). Currently, we don't detect this case
and, if it happens, mheap.sysAlloc will corrupt arena_end and
arena_used then return the low pointer to mheap.grow, which will crash
when it attempts to index in to h_spans with an underflowed index.
Fix this by checking not only that that p+p_size isn't too high, but
that p isn't too low.
Fixes#13143.
Change-Id: I8d0f42bd1484460282a83c6f1a6f8f0df7fb2048
Reviewed-on: https://go-review.googlesource.com/16927
Run-TryBot: Austin Clements <austin@google.com>
TryBot-Result: Gobot Gobot <gobot@golang.org>
Reviewed-by: Ian Lance Taylor <iant@golang.org>
If the area returned by sysReserve in mheap.sysAlloc is outside the
usable arena, we sysFree it. We pass a fake stat pointer to sysFree
because we haven't added the allocation to any stat at that point.
However, we pass a 0 stat, so sysFree panics when it decrements the
stat because the fake stat underflows.
Fix this by setting the fake stat to the allocation size.
Updates #13143 (this is a prerequisite to fixing that bug).
Change-Id: I61a6c9be19ac1c95863cf6a8435e19790c8bfc9a
Reviewed-on: https://go-review.googlesource.com/16926
Reviewed-by: Ian Lance Taylor <iant@golang.org>
golang.org/cl/16346 changed the runtime on linux/386 to invoke the vsyscall
helper via a PIC sequence (CALL 0x10(GS)) when dynamically linking. But it's
actually quite easy to make that code sequence work all the time, so do that,
and remove the ugly machinery that passed the buildmode from the go tool to the
assembly.
This means enlarging m.tls so that we can safely access 0x10(GS) (GS is set to
&m.tls + 4, so 0x10(GS) accesses m_tls[5]).
Change-Id: I1345c34029b149cb5f25320bf19a3cdd73a056fa
Reviewed-on: https://go-review.googlesource.com/16796
Reviewed-by: Ian Lance Taylor <iant@golang.org>
A nosplit comment was added to reflect.typelinks accidentally in
https://golang.org/cl/98510044. There is only one caller of
reflect.typelinks, reflect.typesByString, and that function is not
nosplit. There is no reason for reflect.typelinks to be nosplit.
Change-Id: I0fd3cc66fafcd92643e38e53fa586d6b2f868a0a
Reviewed-on: https://go-review.googlesource.com/16932
Run-TryBot: Ian Lance Taylor <iant@golang.org>
TryBot-Result: Gobot Gobot <gobot@golang.org>
Reviewed-by: Minux Ma <minux@golang.org>
These now live in runtime/internal/sys.
Change-Id: I270597142516512bfc1395419e51d8083ba1663f
Reviewed-on: https://go-review.googlesource.com/16891
Run-TryBot: Matthew Dempsky <mdempsky@google.com>
TryBot-Result: Gobot Gobot <gobot@golang.org>
Reviewed-by: Brad Fitzpatrick <bradfitz@golang.org>
Allows removing fields that aren't relevant to a particular OS or
changing their types to match the underlying OS system calls they'll
be used for.
Change-Id: I5cea89ee77b4e7b985bff41337e561887c3272ff
Reviewed-on: https://go-review.googlesource.com/16176
Reviewed-by: Ian Lance Taylor <iant@golang.org>
Run-TryBot: Matthew Dempsky <mdempsky@google.com>
We're allocating TLS storage for m0 anyway, so might as well use it.
Change-Id: I7dc20bbea5320c8ab8a367f18a9540706751e771
Reviewed-on: https://go-review.googlesource.com/16890
Run-TryBot: Matthew Dempsky <mdempsky@google.com>
TryBot-Result: Gobot Gobot <gobot@golang.org>
Reviewed-by: Michael Hudson-Doyle <michael.hudson@canonical.com>
Reviewed-by: Ian Lance Taylor <iant@golang.org>
This requires changing the tls access code to match the patterns documented in
the ABI documentation or the system linker will "optimize" it into ridiculousness.
With this change, -buildmode=pie works, although as it is tested in testshared,
the tests are not run yet.
Change-Id: I1efa6687af0a5b8db3385b10f6542a49056b2eb3
Reviewed-on: https://go-review.googlesource.com/15971
Reviewed-by: Russ Cox <rsc@golang.org>
The PowerPC ISA does not have a PC-relative load instruction, which poses
obvious challenges when generating position-independent code. The way the ELFv2
ABI addresses this is to specify that r2 points to a per "module" (shared
library or executable) TOC pointer. Maintaining this pointer requires
cooperation between codegen and the system linker:
* Non-leaf functions leave space on the stack at r1+24 to save the TOC pointer.
* A call to a function that *might* have to go via a PLT stub must be followed
by a nop instruction that the system linker can replace with "ld r1, 24(r1)"
to restore the TOC pointer (only when dynamically linking Go code).
* When calling a function via a function pointer, the address of the function
must be in r12, and the first couple of instructions (the "global entry
point") of the called function use this to derive the address of the TOC
for the module it is in.
* When calling a function that is implemented in the same module, the system
linker adjusts the call to skip over the instructions mentioned above (the
"local entry point"), assuming that r2 is already correctly set.
So this changeset adds the global entry point instructions, sets the metadata so
the system linker knows where the local entry point is, inserts code to save the
TOC pointer at 24(r1), adds a nop after any call not known to be local and copes
with the odd non-local code transfer in the runtime (e.g. the stuff around
jmpdefer). It does not actually compile PIC yet.
Change-Id: I7522e22bdfd2f891745a900c60254fe9e372c854
Reviewed-on: https://go-review.googlesource.com/15967
Reviewed-by: Russ Cox <rsc@golang.org>
darwin/386, freebsd/386, and linux/386 use a setldt system call to
setup each M's thread-local storage area, and they need access to the
M's id for this. The current code copies m.id into m.tls[0] (and this
logic has been cargo culted to OSes like NetBSD and OpenBSD, which
don't even need m.id to configure TLS), and then the 386 assembly
loads m.tls[0]... but since the assembly code already has a pointer to
the M, it might as well just load m.id directly.
Change-Id: I1a7278f1ec8ebda8d1de3aa3a61993070e3a8cdf
Reviewed-on: https://go-review.googlesource.com/16881
Run-TryBot: Matthew Dempsky <mdempsky@google.com>
TryBot-Result: Gobot Gobot <gobot@golang.org>
Reviewed-by: Ian Lance Taylor <iant@golang.org>
The larger stack frames causes the nosplit stack to overflow so the next change
increases the stackguard.
Change-Id: Ib2b4f24f0649eb1d13e3a58d265f13d1b6cc9bf9
Reviewed-on: https://go-review.googlesource.com/15964
Reviewed-by: Russ Cox <rsc@golang.org>
Larger stack frames mean nosplit functions use more stack and so the limit
needs to increase.
The change to test/nosplit.go is a bit ugly but I can't really think of a
way to make it nicer.
Change-Id: I2616b58015f0b62abbd62951575fcd0d2d8643c2
Reviewed-on: https://go-review.googlesource.com/16504
Reviewed-by: Russ Cox <rsc@golang.org>
Apparently its last use was removed in CL 8899.
Change-Id: I4f3a789b3cc4c249582e81463af62b576a281e40
Reviewed-on: https://go-review.googlesource.com/16880
Run-TryBot: Matthew Dempsky <mdempsky@google.com>
Reviewed-by: Minux Ma <minux@golang.org>
Reviewed-by: Brad Fitzpatrick <bradfitz@golang.org>
TryBot-Result: Gobot Gobot <gobot@golang.org>
The new revision is 389d49d4943780efbfcd2a434f4462b6d0f23c44 (Nov 13, 2015).
The runtimes are built using the new x/build/cmd/racebuild utility.
This update fixes a bug in race detection algorithm that can
lead to occasional false negatives (#10589). But generally just
brings in an up-to-date runtime.
Update #8653Fixes#10589
Change-Id: I7ac9614d014ee89c2302ce5e096d326ef293f367
Reviewed-on: https://go-review.googlesource.com/16827
Reviewed-by: Keith Randall <khr@golang.org>
As per mdempsky's comment on golang.org/cl/14204, textflag.h is
copied to the includes dir by cmd/dist, and the copy in
runtime/internal/atomic is not actually being used.
Updates #11647
Change-Id: Ie95c08903a9df54cea4c70ee9d5291176f7b5609
Reviewed-on: https://go-review.googlesource.com/16871
Run-TryBot: Michael Matloob <matloob@golang.org>
TryBot-Result: Gobot Gobot <gobot@golang.org>
Reviewed-by: Matthew Dempsky <mdempsky@google.com>
Somehow these were left out of the orignial CL.
Updates #11647
Change-Id: I058a30eaa25fbb72d60e7fb6bc9ff0a3b54fdb2a
Reviewed-on: https://go-review.googlesource.com/16870
Reviewed-by: Minux Ma <minux@golang.org>
I made a copy of the per-arch _CacheLineSize definitons when checking in
runtime/internal/atomic. Now that runtime/internal/sys is checked in,
we can use the definition there.
Change-Id: I7242f6b633e4164f033b67ff471416b9d71c64d2
Reviewed-on: https://go-review.googlesource.com/16847
Reviewed-by: Brad Fitzpatrick <bradfitz@golang.org>
sigprof tracebacks the stack across systemstack switches to make
profile tracebacks more complete. However, it does this even if the
user stack is currently being copied, which means it may be in an
inconsistent state that will cause the traceback to panic.
One specific way this can happen is during stack shrinking. Some
goroutine blocks for STW, then enters gchelper, which then assists
with root marking. If that root marking happens to pick the original
goroutine and its stack needs to be shrunk, it will begin to copy that
stack. During this copy, the stack is generally inconsistent and, in
particular, the actual locations of the stack barriers and their
recorded locations are temporarily out of sync. If a SIGPROF happens
during this inconsistency, it will walk the stack all the way back to
the blocked goroutine and panic when it fails to unwind the stack
barriers.
Fix this by disallowing jumping to the user stack during SIGPROF if
that user stack is in the process of being copied.
Fixes#12932.
Change-Id: I9ef694c2c01e3653e292ce22612418dd3daff1b4
Reviewed-on: https://go-review.googlesource.com/16819
Reviewed-by: Daniel Morsing <daniel.morsing@gmail.com>
Run-TryBot: Austin Clements <austin@google.com>
TryBot-Result: Gobot Gobot <gobot@golang.org>
runtime/internal/sys will hold system-, architecture- and config-
specific constants.
Updates #11647
Change-Id: I6db29c312556087a42e8d2bdd9af40d157c56b54
Reviewed-on: https://go-review.googlesource.com/16817
Reviewed-by: Russ Cox <rsc@golang.org>
cgo_ppc64x.go:7: +build comment must appear before package clause and be followed by a blank line
Change-Id: Ib6dedddae70cc75dc3f137eb37ea338a64f8b595
Reviewed-on: https://go-review.googlesource.com/16835
Run-TryBot: Matthew Dempsky <mdempsky@google.com>
Reviewed-by: Andrew Gerrand <adg@golang.org>
TryBot-Result: Gobot Gobot <gobot@golang.org>
Change-Id: I419f3b8bf1bddffd4a775b0cd7b98f0239fe19cb
Reviewed-on: https://go-review.googlesource.com/14458
Reviewed-by: Minux Ma <minux@golang.org>
Reviewed-by: Ian Lance Taylor <iant@golang.org>
Linux/mips64 uses a different signal table. To avoid code copying,
signal table is factored out from signal_linux.go to
sigtab_linux_generic.go. And a mips64-specific version is added.
Change-Id: I842d7a7467c330bf772855fde01aecc77a42316b
Reviewed-on: https://go-review.googlesource.com/14993
Reviewed-by: Ian Lance Taylor <iant@golang.org>
Linux/mips64 has a different sigset type and some different constants.
os2_linux.go is renamed to os2_linux_generic.go, and not used in mips64.
The corresponding file os2_linux_mips64x.go is added.
Change-Id: Ief83845a2779f7fe048d236d3c7da52b627ab533
Reviewed-on: https://go-review.googlesource.com/14992
Reviewed-by: Minux Ma <minux@golang.org>
Linux/mips64 uses a different type of sigset. To deal with it, related
functions in os1_linux.go is refactored to os1_linux_generic.go
(used for non-mips64 architectures), and os1_linux_mips64x.go (only used
in mips64{,le}), to avoid code copying.
Change-Id: I5cadfccd86bfc4b30bf97e12607c3c614903ea4c
Reviewed-on: https://go-review.googlesource.com/14991
Reviewed-by: Ian Lance Taylor <iant@golang.org>
Change-Id: I381c03d957a0dccae5f655f02e92760e5c0e9629
Reviewed-on: https://go-review.googlesource.com/14929
Reviewed-by: Ian Lance Taylor <iant@golang.org>
Reviewed-by: Minux Ma <minux@golang.org>
files for unsupported architectures are deleted, as it would require
changing cmd/dist to recognize their names as build tags (probably
need a separated CL).
Change-Id: Ifd164b014867d39b4924d1b859fb84317dce4ab0
Reviewed-on: https://go-review.googlesource.com/14928
Reviewed-by: Ian Lance Taylor <iant@golang.org>
Reviewed-by: Minux Ma <minux@golang.org>
Applies to types fixAlloc, mCache, mCentral, mHeap, mSpan, and
mSpanList.
Two special cases:
1. mHeap_Scavenge() previously didn't take an *mheap parameter, so it
was specially handled in this CL.
2. mHeap_Free() would have collided with mheap's "free" field, so it's
been renamed to (*mheap).freeSpan to parallel its underlying
(*mheap).freeSpanLocked method.
Change-Id: I325938554cca432c166fe9d9d689af2bbd68de4b
Reviewed-on: https://go-review.googlesource.com/16221
Reviewed-by: Ian Lance Taylor <iant@golang.org>
Run-TryBot: Matthew Dempsky <mdempsky@google.com>
TryBot-Result: Gobot Gobot <gobot@golang.org>
It was disabled because of the lack of external linking.
Change-Id: Iccb4a4ef8c57d048d53deabe4e0f4e6b9dccce33
Reviewed-on: https://go-review.googlesource.com/16797
Reviewed-by: Ian Lance Taylor <iant@golang.org>
The GC now handles the root marking jobs as part of general marking,
so work.markfor is no longer used.
Change-Id: I6c3b23fed27e4e7ea6430d6ca7ba25ae4d04ed14
Reviewed-on: https://go-review.googlesource.com/16811
Run-TryBot: Austin Clements <austin@google.com>
TryBot-Result: Gobot Gobot <gobot@golang.org>
Reviewed-by: Brad Fitzpatrick <bradfitz@golang.org>
When we're jumping time forward, it means everyone is asleep, so there
should always be an M available. Furthermore, this causes both
allocation and write barriers in contexts that may be running without
a P (such as in sysmon).
Hence, replace this allocation with a throw.
Updates #10600.
Change-Id: I2cee70d5db828d0044082878995949edb25dda5f
Reviewed-on: https://go-review.googlesource.com/16815
Reviewed-by: Russ Cox <rsc@golang.org>
Currently traceBuf keeps track of where it is in the trace buffer by
also maintaining a slice that points in to this buffer with an initial
length of 0 and a cap of the length of the array. All writes to this
buffer are done by appending to the slice (as long as the bounds
checks are right, it will never overflow and the append won't allocate
a new slice).
Each of these appends generates a write barrier. As long as we never
overflow the buffer, this write barrier won't fire, but this wreaks
havoc with eliminating write barriers from the tracing code. If we
were to overflow the buffer, this would both allocate and invoke a
write barrier, both things that are dicey at best to do in many of the
contexts tracing happens. It also wastes space in the traceBuf and
leads to more complex code and more complex generated code.
Replace this slice trick with keeping track of a simple array
position.
Updates #10600.
Change-Id: I0a63eecec1992e195449f414ed47653f66318d0e
Reviewed-on: https://go-review.googlesource.com/16814
Run-TryBot: Austin Clements <austin@google.com>
TryBot-Result: Gobot Gobot <gobot@golang.org>
Reviewed-by: Dmitry Vyukov <dvyukov@google.com>
The tracing code is currently called from contexts such as sysmon and
the scheduler where write barriers are not allowed. Unfortunately,
while the common paths through the tracing code do not have write
barriers, many of the less common paths dealing with buffer overflow
and recycling do.
This change replaces all *traceBufs with traceBufPtrs. In the style of
guintptr, etc., the GC does not trace traceBufPtrs and write barriers
do not apply when these pointers are written. Since traceBufs are
allocated from non-GC'd memory and manually managed, this is always
safe.
Updates #10600.
Change-Id: I52b992d36d1b634ebd855c8cde27947ec14f59ba
Reviewed-on: https://go-review.googlesource.com/16812
Run-TryBot: Austin Clements <austin@google.com>
TryBot-Result: Gobot Gobot <gobot@golang.org>
Reviewed-by: Dmitry Vyukov <dvyukov@google.com>
Commit 7407d8e was rebased over the switch to runtime/internal/atomic
and introduced a call to xadd64, which no longer exists. Fix that
call.
Change-Id: I99c93469794c16504ae4a8ffe3066ac382c66a3a
Reviewed-on: https://go-review.googlesource.com/16816
Reviewed-by: Brad Fitzpatrick <bradfitz@golang.org>
Reviewed-by: Rick Hudson <rlh@golang.org>
Currently, sweeping is performed before allocating a span by charging
for the entire size of the span requested, rather than the number of
bytes actually available for allocation from the returned span. That
is, if the returned span is 8K, but already has 6K in use, the mutator
is charged for 8K of heap allocation even though it can only allocate
2K more from the span. As a result, proportional sweep is
over-aggressive and tends to finish much earlier than it needs to.
This effect is more amplified by fragmented heaps.
Fix this by reimbursing the mutator for the used space in a span once
it has allocated that span. We still have to charge up-front for the
worst-case because we don't know which span the mutator will get, but
at least we can correct the over-charge once it has a span, which will
go toward later span allocations.
This has negligible effect on the throughput of the go1 benchmarks and
the garbage benchmark.
Fixes#12040.
Change-Id: I0e23e7a4ccf126cca000fed5067b20017028dd6b
Reviewed-on: https://go-review.googlesource.com/16515
Reviewed-by: Rick Hudson <rlh@golang.org>
The runtime is not instrumented, but the calls to msanread in the
runtime can sometimes refer to the system stack. An example is the call
to copy in stkbucket in mprof.go. Depending on what C code has done,
the system stack may appear uninitialized to msan.
Change-Id: Ic21705b9ac504ae5cf7601a59189302f072e7db1
Reviewed-on: https://go-review.googlesource.com/16660
Reviewed-by: David Crawshaw <crawshaw@golang.org>
This is a fix for the -msan option when using cgo callbacks. A cgo
callback works by writing out C code that puts a struct on the stack and
passes the address of that struct into Go. The result parameters are
fields of the struct. The Go code will write to the result parameters,
but the Go code thinks it is just writing into the Go stack, and
therefore won't call msanwrite. This CL adds a call to msanwrite in the
cgo callback code so that the C knows that results were written.
Change-Id: I80438dbd4561502bdee97fad3f02893a06880ee1
Reviewed-on: https://go-review.googlesource.com/16611
Reviewed-by: David Crawshaw <crawshaw@golang.org>
This changes "mark worker (idle)" to "GC worker (idle)" so it's more
clear to users that these goroutines are GC-related. It changes "GC
assist" to "GC assist wait" to make it clear that the assist is
blocked.
Change-Id: Iafbc0903c84f9250ff6bee14baac6fcd4ed5ef76
Reviewed-on: https://go-review.googlesource.com/16511
Reviewed-by: Rick Hudson <rlh@golang.org>
We couldn't do this before this point because it must be done before
the next GC cycle starts. Hence, if it delayed the start of the next
cycle, that would widen the window between reaching the heap trigger
of the next cycle and starting the next GC cycle, during which the
mutator could over-allocate. With the decentralized GC, any mutators
that reach the heap trigger will block on the GC starting, so it's
safe to widen the time between starting the world and being able to
start the next GC cycle.
Fixes#11465.
Change-Id: Ic7ea7e9eba5b66fc050299f843a9c9001ad814aa
Reviewed-on: https://go-review.googlesource.com/16394
Reviewed-by: Rick Hudson <rlh@golang.org>
Run-TryBot: Austin Clements <austin@google.com>
TryBot-Result: Gobot Gobot <gobot@golang.org>
This implements part of the proposal in issue 12416 by adding dynamic
checks for passing pointers from Go to C. This code is intended to be
on at all times. It does not try to catch every case. It does not
implement checks on calling Go functions from C.
The new cgo checks may be disabled using GODEBUG=cgocheck=0.
Update #12416.
Change-Id: I48de130e7e2e83fb99a1e176b2c856be38a4d3c8
Reviewed-on: https://go-review.googlesource.com/16003
Reviewed-by: Russ Cox <rsc@golang.org>
This change breaks out most of the atomics functions in the runtime
into package runtime/internal/atomic. It adds some basic support
in the toolchain for runtime packages, and also modifies linux/arm
atomics to remove the dependency on the runtime's mutex. The mutexes
have been replaced with spinlocks.
all trybots are happy!
In addition to the trybots, I've tested on the darwin/arm64 builder,
on the darwin/arm builder, and on a ppc64le machine.
Change-Id: I6698c8e3cf3834f55ce5824059f44d00dc8e3c2f
Reviewed-on: https://go-review.googlesource.com/14204
Run-TryBot: Michael Matloob <matloob@golang.org>
Reviewed-by: Russ Cox <rsc@golang.org>
This change is the same as CL #9345 which was reverted,
except for a small bug fix.
The only change is to the body of sendDirect and its callsite.
Also added a test.
The problem was during a channel send operation. The target
of the send was a sleeping goroutine waiting to receive. We
basically do:
1) Read the destination pointer out of the sudog structure
2) Copy the value we're sending to that destination pointer
Unfortunately, the previous change had a goroutine suspend
point between 1 & 2 (the call to sendDirect). At that point
the destination goroutine's stack could be copied (shrunk).
The pointer we read in step 1 is no longer valid for step 2.
Fixed by not allowing any suspension points between 1 & 2.
I suspect the old code worked correctly basically by accident.
Fixes#13169
The original 9345:
This change removes the retry mechanism we use for buffered channels.
Instead, any sender waking up a receiver or vice versa completes the
full protocol with its counterpart. This means the counterpart does
not need to relock the channel when it wakes up. (Currently
buffered channels need to relock on wakeup.)
For sends on a channel with waiting receivers, this change replaces
two copies (sender->queue, queue->receiver) with one (sender->receiver).
For receives on channels with a waiting sender, two copies are still required.
This change unifies to a large degree the algorithm for buffered
and unbuffered channels, simplifying the overall implementation.
Fixes#11506
Change-Id: I57dfa3fc219cffa4d48301ee15fe5479299efa09
Reviewed-on: https://go-review.googlesource.com/16740
Reviewed-by: Ian Lance Taylor <iant@golang.org>
Other systems use pthread_sigmask. It was a mistake to use sigprocmask
here.
Change-Id: Ie045aa3f09cf035fcf807b7543b96fa5b847958a
Reviewed-on: https://go-review.googlesource.com/16720
Reviewed-by: Dave Cheney <dave@cheney.net>
Reviewed-by: David Crawshaw <crawshaw@golang.org>
Run-TryBot: Ian Lance Taylor <iant@golang.org>
TryBot-Result: Gobot Gobot <gobot@golang.org>
Make sure that we're moving or zeroing pointers atomically.
Anything that is a multiple of pointer size and at least
pointer aligned might have pointers in it. All the code looks
ok except for the 1-pointer-sized moves.
Fixes#13160
Update #12552
Change-Id: Ib97d9b918fa9f4cc5c56c67ed90255b7fdfb7b45
Reviewed-on: https://go-review.googlesource.com/16668
Reviewed-by: Dmitry Vyukov <dvyukov@google.com>
Run-TryBot: Keith Randall <khr@golang.org>
TryBot-Result: Gobot Gobot <gobot@golang.org>
Revert for now until #13169 is understood.
This reverts commit 8e496f1d69.
Change-Id: Ib3eb2588824ef47a2b6eb9e377a24e5c817fcc81
Reviewed-on: https://go-review.googlesource.com/16716
Reviewed-by: Keith Randall <khr@golang.org>
Currently mallocgc detects if the GC is in a state where it can't
assist, but also can't allocate uncontrolled and yields to help out
the GC. This was a workaround for periods when we were trying to
schedule the GC coordinator. It is no longer necessary because there
is no GC coordinator and malloc can always assist with any GC
transitions that are necessary.
Updates #11970.
Change-Id: I4f7beb7013e85e50ae99a3a8b0bb708ba49cbcd4
Reviewed-on: https://go-review.googlesource.com/16392
Reviewed-by: Rick Hudson <rlh@golang.org>
Run-TryBot: Austin Clements <austin@google.com>
TryBot-Result: Gobot Gobot <gobot@golang.org>
This moves all of the mark 1 to mark 2 transition and mark termination
to the mark done transition function. This means these transitions are
now handled on the goroutine that detected mark completion. This also
means that the GC coordinator and the background completion barriers
are no longer used and various workarounds to yield to the coordinator
are no longer necessary. These will be removed in follow-up commits.
One consequence of this is that mark workers now need to be
preemptible when performing the mark done transition. This allows them
to stop the world and to perform the final clean-up steps of GC after
restarting the world. They are only made preemptible while performing
this transition, so if the worker findRunnableGCWorker would schedule
isn't available, we didn't want to schedule it anyway.
Fixes#11970.
Change-Id: I9203a2d6287eeff62d589ec02ad9cb1e29ddb837
Reviewed-on: https://go-review.googlesource.com/16391
Reviewed-by: Rick Hudson <rlh@golang.org>
Run-TryBot: Austin Clements <austin@google.com>
TryBot-Result: Gobot Gobot <gobot@golang.org>
Currently gcMarkDone takes basically no time, so it's okay to account
the worker time after calling it. However, gcMarkDone is about to take
potentially *much* longer because it may perform all of mark
termination. Prepare for this by swapping the order so we account the
time before calling gcMarkDone.
Change-Id: I90c7df68192acfc4fd02a7254dae739dda4e2fcb
Reviewed-on: https://go-review.googlesource.com/16390
Reviewed-by: Rick Hudson <rlh@golang.org>
Run-TryBot: Austin Clements <austin@google.com>
TryBot-Result: Gobot Gobot <gobot@golang.org>
Currently the code for completion of mark 1/mark 2 is duplicated in
background workers and assists. Factor this in to a single function
that will serve as the transition function for concurrent mark.
Change-Id: I4d9f697a15da0d349db3b34d56f3a220dd41d41b
Reviewed-on: https://go-review.googlesource.com/16359
Reviewed-by: Rick Hudson <rlh@golang.org>
Run-TryBot: Austin Clements <austin@google.com>
TryBot-Result: Gobot Gobot <gobot@golang.org>
Currently, findRunnableGCWorker will perform mark completion if there
is no remaining work and no running workers. This used to be necessary
to resolve a race in the transition from mark 1 to mark 2 where we
would enter mark 2 with no mark work (and no dedicated workers), so no
workers would run, so no worker would signal mark completion.
However, we're about to make mark completion also perform the entire
follow-on process, which includes mark termination. We really don't
want to do that in the scheduler if it happens to detect completion.
Conveniently, this hack is no longer necessary because we always
enqueue root scanning work at the beginning of both mark 1 and mark 2,
so a mark worker will always run. Hence, we can simply eliminate it.
Change-Id: I3fc8f27c8da632f0fb732c9f6425e1f457f5652e
Reviewed-on: https://go-review.googlesource.com/16358
Reviewed-by: Rick Hudson <rlh@golang.org>
Run-TryBot: Austin Clements <austin@google.com>
TryBot-Result: Gobot Gobot <gobot@golang.org>
Currently, we don't start dedicated or fractional mark workers unless
the mark 1 or mark 2 barriers have been cleared. One intended
consequence of this is that no background workers run between the
forEachP that disposes all gcWork caches and the beginning of mark 2.
However, we (unintentionally) did not apply this restriction to idle
mark workers. As a result, these can start in the interim between mark
1 completion and mark 2 starting. This explains why it was necessary
to reset the root marking jobs using carefully ordered atomic writes
when setting up mark 2. It also means that, even though we definitely
enqueue work before starting mark 2, it may be drained by the time we
reset the mark 2 barrier. If this happens, currently the only thing
preventing the runtime from deadlocking is that the scheduler itself
also checks for mark completion and will signal mark 2 completion.
Were it not for the odd behavior of idle workers, this check in the
scheduler would not be necessary.
Clean all of this up and prepare to remove this check in the scheduler
by applying the same restriction to starting idle mark workers.
Change-Id: Ic1b479e1591bd7773dc27b320ca399a215603b5a
Reviewed-on: https://go-review.googlesource.com/16631
Reviewed-by: Rick Hudson <rlh@golang.org>
Run-TryBot: Austin Clements <austin@google.com>
TryBot-Result: Gobot Gobot <gobot@golang.org>
This moves all of GC initialization, sweep termination, and the
transition to concurrent marking in to the off->mark transition
function. This means it's now handled on the goroutine that detected
the state exit condition.
As a result, malloc no longer needs to Gosched() at the beginning of
the GC cycle to prevent over-allocation while the GC is starting up
because it will now *help* the GC to start up. The Gosched hack is
still necessary during GC shutdown (this is easy to test by enabling
gctrace and hitting Ctrl-S to block the gctrace output).
At this point, the GC coordinator still handles later phases. This
requires a small tweak to how we start the GC coordinator. Currently,
starting the GC coordinator is best-effort and may fail if the
coordinator is about to park from the previous cycle but hasn't yet.
We fix this by replacing the park/ready to wake up the coordinator
with a semaphore. This is temporary since the coordinator will be
going away in a few commits.
Updates #11970.
Change-Id: I2c6a11c91e72dfbc59c2d8e7c66146dee9a444fe
Reviewed-on: https://go-review.googlesource.com/16357
Reviewed-by: Rick Hudson <rlh@golang.org>
Run-TryBot: Austin Clements <austin@google.com>
TryBot-Result: Gobot Gobot <gobot@golang.org>
This moves concurrent sweep termination from the coordinator to the
off->mark transition. This allows it to be performed by all Gs
attempting to start the GC.
Updates #11970.
Change-Id: I24428e8599a759398c2ef7ec996ba755a448f947
Reviewed-on: https://go-review.googlesource.com/16356
Reviewed-by: Rick Hudson <rlh@golang.org>
Run-TryBot: Austin Clements <austin@google.com>
TryBot-Result: Gobot Gobot <gobot@golang.org>
This begins the conversion of the centralized GC coordinator to a
decentralized state machine by introducing the internal API that
triggers the first state transition from _GCoff to _GCmark (or
_GCmarktermination).
This change introduces the transition lock, the off->mark transition
condition (which is very similar to shouldtriggergc()), and the
general structure of a state transition. Since we're doing this
conversion in stages, it then falls back to the GC coordinator to
actually execute the cycle. We'll start moving logic out of the GC
coordinator and in to transition functions next.
This fixes a minor bug in gcstoptheworld debug mode where passing the
heap trigger once could trigger multiple STW GCs.
Updates #11970.
Change-Id: I964087dd190a639eb5766398f8e1bbf8b352902f
Reviewed-on: https://go-review.googlesource.com/16355
Reviewed-by: Rick Hudson <rlh@golang.org>
Run-TryBot: Austin Clements <austin@google.com>
For historical reasons we currently do a lot of the concurrent mark
setup on the system stack. In fact, at this point the one and only
thing that needs to happen on the system stack is the start-the-world.
Clean up this code by lifting everything other than the
start-the-world off the system stack.
The diff for this change looks large, but the only code change is to
narrow the systemstack call. Everything else is re-indentation.
Change-Id: I1e03b8afc759fad726f2397b05a17d183c2713ce
Reviewed-on: https://go-review.googlesource.com/16354
Reviewed-by: Rick Hudson <rlh@golang.org>
Run-TryBot: Austin Clements <austin@google.com>
TryBot-Result: Gobot Gobot <gobot@golang.org>
We're about to split func gc across several functions, so lift the
local variables it uses for tracking statistics and state across the
cycle into the global "work" variable.
Change-Id: Ie955f2f1758c7f5a5543ea1f3f33b222bc4b1d37
Reviewed-on: https://go-review.googlesource.com/16353
Reviewed-by: Rick Hudson <rlh@golang.org>
Run-TryBot: Austin Clements <austin@google.com>
TryBot-Result: Gobot Gobot <gobot@golang.org>
This change removes the retry mechanism we use for buffered channels.
Instead, any sender waking up a receiver or vice versa completes the
full protocol with its counterpart. This means the counterpart does
not need to relock the channel when it wakes up. (Currently
buffered channels need to relock on wakeup.)
For sends on a channel with waiting receivers, this change replaces
two copies (sender->queue, queue->receiver) with one (sender->receiver).
For receives on channels with a waiting sender, two copies are still required.
This change unifies to a large degree the algorithm for buffered
and unbuffered channels, simplifying the overall implementation.
Fixes#11506
benchmark old ns/op new ns/op delta
BenchmarkChanProdCons10 125 110 -12.00%
BenchmarkChanProdCons0 303 284 -6.27%
BenchmarkChanProdCons100 75.5 71.3 -5.56%
BenchmarkChanContended 6452 6125 -5.07%
BenchmarkChanNonblocking 11.5 11.0 -4.35%
BenchmarkChanCreation 149 143 -4.03%
BenchmarkChanSem 63.6 61.6 -3.14%
BenchmarkChanUncontended 6390 6212 -2.79%
BenchmarkChanSync 282 276 -2.13%
BenchmarkChanProdConsWork10 516 506 -1.94%
BenchmarkChanProdConsWork0 696 685 -1.58%
BenchmarkChanProdConsWork100 470 469 -0.21%
BenchmarkChanPopular 660427 660012 -0.06%
Change-Id: I164113a56432fbc7cace0786e49c5a6e6a708ea4
Reviewed-on: https://go-review.googlesource.com/9345
Run-TryBot: Keith Randall <khr@golang.org>
Reviewed-by: Austin Clements <austin@google.com>
Reviewed-by: Dmitry Vyukov <dvyukov@google.com>
Currently dedicated mark workers participate in the getfull barrier
during concurrent mark. However, the getfull barrier wasn't designed
for concurrent work and this causes no end of headaches.
In the concurrent setting, participants come and go. This makes mark
completion susceptible to live-lock: since dedicated workers are only
periodically polling for completion, it's possible for the program to
be in some transient worker each time one of the dedicated workers
wakes up to check if it can exit the getfull barrier. It also
complicates reasoning about the system because dedicated workers
participate directly in the getfull barrier, but transient workers
must instead use trygetfull because they have exit conditions that
aren't captured by getfull (e.g., fractional workers exit when
preempted). The complexity of implementing these exit conditions
contributed to #11677. Furthermore, the getfull barrier is inefficient
because we could be running user code instead of spinning on a P. In
effect, we're dedicating 25% of the CPU to marking even if that means
we have to spin to make that 25%. It also causes issues on Windows
because we can't actually sleep for 100µs (#8687).
Fix this by making dedicated workers no longer participate in the
getfull barrier. Instead, dedicated workers simply return to the
scheduler when they fail to get more work, regardless of what others
workers are doing, and the scheduler only starts new dedicated workers
if there's work available. Everything that needs to be handled by this
barrier is already handled by detection of mark completion.
This makes the system much more symmetric because all workers and
assists now use trygetfull during concurrent mark. It also loosens the
25% CPU target so that we can give some of that 25% back to user code
if there isn't enough work to keep the mark worker busy. And it
eliminates the problematic 100µs sleep on Windows during concurrent
mark (though not during mark termination).
The downside of this is that if we hit a bottleneck in the heap graph
that then expands back out, the system may shut down dedicated workers
and take a while to start them back up. We'll address this in the next
commit.
Updates #12041 and #8687.
No effect on the go1 benchmarks. This slows down the garbage benchmark
by 9%, but we'll more than make it up in the next commit.
name old time/op new time/op delta
XBenchGarbage-12 5.80ms ± 2% 6.32ms ± 4% +9.03% (p=0.000 n=20+20)
Change-Id: I65100a9ba005a8b5cf97940798918672ea9dd09b
Reviewed-on: https://go-review.googlesource.com/16297
Reviewed-by: Rick Hudson <rlh@golang.org>
This introduces a recursive variant of the go:nowritebarrier
annotation that prohibits write barriers not only in the annotated
function, but in all functions it calls, recursively. The error
message gives the shortest call stack from the annotated function to
the function containing the prohibited write barrier, including the
names of the functions and the line numbers of the calls.
To demonstrate the annotation, we apply it to gcmarkwb_m, the write
barrier itself.
This is a new annotation rather than a modification of the existing
go:nowritebarrier annotation because, for better or worse, there are
many go:nowritebarrier functions that do call functions with write
barriers. In most of these cases this is benign because the annotation
was conservative, but it prohibits simply coopting the existing
annotation.
Change-Id: I225ca483c8f699e8436373ed96349e80ca2c2479
Reviewed-on: https://go-review.googlesource.com/16554
Reviewed-by: Keith Randall <khr@golang.org>
Handling of special records for tiny allocations has two problems:
1. Once we queue a finalizer we mark the object. As the result any
subsequent finalizers for the same object will not be queued
during this GC cycle. If we have 16 finalizers setup (the worst case),
finalization will take 16 GC cycles. This is what caused misbehave
of tinyfin.go. The actual flakiness was caused by the fact that fing
is asynchronous and don't always run before the check.
2. If a tiny block has both finalizer and profile specials,
it is possible that we both queue finalizer, preserve the object live
and free the profile record. As the result heap profile can be skewed.
Fix both issues by analyzing all special records for a single object at once.
Also, make tinyfin test stricter and remove reliance on real time.
Also, add a test for the problem 2. Currently heap profile missed about
a half of live memory.
Fixes#13100
Change-Id: I9ae4dc1c44893724138a4565ca5cae29f2e97544
Reviewed-on: https://go-review.googlesource.com/16591
Reviewed-by: Austin Clements <austin@google.com>
Reviewed-by: Keith Randall <khr@golang.org>
Run-TryBot: Dmitry Vyukov <dvyukov@google.com>
Declare a function's arguments as having already been
spilled so their use just requires a restore.
Allow spill locations to be portions of larger objects the stack.
Required to load portions of compound input arguments.
Rename the memory input to InputMem. Use Arg for the
pre-spilled argument values.
Change-Id: I8fe2a03ffbba1022d98bfae2052b376b96d32dda
Reviewed-on: https://go-review.googlesource.com/16536
Run-TryBot: Keith Randall <khr@golang.org>
TryBot-Result: Gobot Gobot <gobot@golang.org>
Reviewed-by: David Chase <drchase@google.com>
Currently the GC work buffers are only 256 bytes and hence can record
only 24 64-bit pointer. They were reduced from 4K in commits db7fd1c
and a15818f as a way to minimize the amount of work the per-P workbuf
caches could "hide" from the mark phase and carry in to the mark
termination phase. However, this approach wasn't very robust and we
later added a "mark 2" phase to address this problem head-on.
Because of mark 2, there's now no benefit to having very small work
buffers. But there are plenty of downsides: small work buffers
increase contention on the work lists, increase the frequency and
hence net overhead of acquiring and releasing work buffers, and
somewhat increase memory overhead of the GC.
This commit expands work buffers back to 4K (504 64-bit pointers).
This reduces the rate of writes to work.full in the garbage benchmark
from a peak of ~780,000 writes/sec to a peak of ~32,000 writes/sec.
This has negligible effect on the go1 benchmarks. It slightly slows
down the garbage benchmark.
name old time/op new time/op delta
XBenchGarbage-12 5.37ms ± 5% 5.60ms ± 2% +4.37% (p=0.000 n=20+20)
Change-Id: Ic9cc28e7a125d23d9faf4f5e690fb8aa9bcdfb28
Reviewed-on: https://go-review.googlesource.com/15893
Reviewed-by: Rick Hudson <rlh@golang.org>
Run-TryBot: Austin Clements <austin@google.com>
TryBot-Result: Gobot Gobot <gobot@golang.org>
Currently, assists are non-preemptible, which means a heavily
assisting G can block other Gs from running. At the beginning of a GC
cycle, it can also delay scang, which will spin until the assist is
done. Since scanning is currently done sequentially, this can
seriously extend the length of the scan phase.
Fix this by making assists preemptible. Since the assist holds work
buffers and runs on the system stack, this must be done cooperatively:
we make gcDrainN return on preemption, and make the assist return from
the system stack and voluntarily Gosched.
This is prerequisite to enlarging the work buffers. Without this
change, the delays and spinning in scang increase significantly.
This has no effect on the go1 benchmarks.
name old time/op new time/op delta
XBenchGarbage-12 5.72ms ± 4% 5.37ms ± 5% -6.11% (p=0.000 n=20+20)
Change-Id: I829e732a0f23b126da633516a1a9ec1a508fdbf1
Reviewed-on: https://go-review.googlesource.com/15894
Reviewed-by: Rick Hudson <rlh@golang.org>
Run-TryBot: Austin Clements <austin@google.com>
TryBot-Result: Gobot Gobot <gobot@golang.org>
GC assists must block until the assist can be satisfied (either
through stealing credit or doing work) or the GC cycle ends.
Currently, this is implemented as a retry loop with a 100 µs delay.
This obviously isn't ideal, as it wastes CPU and delays mutator
execution. It also has the somewhat peculiar downside that sleeping a
G requires allocation, and this requires working around recursive
allocation.
Replace this timed delay with a proper scheduling queue. When an
assist can't be satisfied immediately, it adds the allocating G to a
queue and parks it. Any time background scan credit is flushed, it
consults this queue, directly satisfies the debt of queued assists,
and wakes up satisfied assists before flushing any remaining credit to
the background credit pool.
No effect on the go1 benchmarks. Slightly speeds up the garbage
benchmark.
name old time/op new time/op delta
XBenchGarbage-12 5.81ms ± 1% 5.72ms ± 4% -1.65% (p=0.011 n=20+20)
Updates #12041.
Change-Id: I8ee3b6274dd097b12b10a8030796a958a4b0e7b7
Reviewed-on: https://go-review.googlesource.com/15890
Reviewed-by: Rick Hudson <rlh@golang.org>
Run-TryBot: Austin Clements <austin@google.com>
TryBot-Result: Gobot Gobot <gobot@golang.org>
This eliminates many write barriers in the scheduler code that are
unnecessary and will interfere with upcoming changes where the garbage
collector will have to invoke run queue functions in contexts that
must not have write barriers.
Change-Id: I702d0ac99cfd00ffff406e7362917db6a43e7e55
Reviewed-on: https://go-review.googlesource.com/16556
Reviewed-by: Russ Cox <rsc@golang.org>
Run-TryBot: Austin Clements <austin@google.com>
To avoid collisions with what existing code may already be doing.
Change-Id: Ice639440aafc0724714c25333d90a49954372230
Reviewed-on: https://go-review.googlesource.com/16503
Reviewed-by: Ian Lance Taylor <iant@golang.org>
Currently the concurrent root scan is performed in its entirety by the
GC coordinator before entering concurrent mark (which enables GC
workers). This scan is done sequentially, which can prolong the scan
phase, delay the mark phase, and means that the scan phase does not
obey the 25% CPU goal. Furthermore, there's no need to complete the
root scan before starting marking (in fact, we already allow GC
assists to happen during the scan phase), so this acts as an
unnecessary barrier between root scanning and marking.
This change shifts the root scan work out of the GC coordinator and in
to the GC workers. The coordinator simply sets up the scan state and
enqueues the right number of root scan jobs. The GC workers then drain
the root scan jobs prior to draining heap scan jobs.
This parallelizes the root scan process, makes it obey the 25% CPU
goal, and effectively eliminates root scanning as an isolated phase,
allowing the system to smoothly transition from root scanning to heap
marking. This also eliminates a major non-STW responsibility of the GC
coordinator, which will make it easier to switch to a decentralized
state machine. Finally, it puts us in a good position to perform root
scanning in assists as well, which will help satisfy assists at the
beginning of the GC cycle.
This is mostly straightforward. One tricky aspect is that we have to
deal with preemption deadlock: where two non-preemptible gorountines
are trying to preempt each other to perform a stack scan. Given the
context where this happens, the only instance of this is two
background workers trying to scan each other. We avoid this by simply
not scanning the stacks of background workers during the concurrent
phase; this is safe because we'll scan them during mark termination
(and their stacks are *very* small and should not contain any new
pointers).
This change also switches the root marking during mark termination to
use the same gcDrain-based code path as concurrent mark. This
shouldn't affect performance because STW root marking was already
parallel and tasks switched to heap marking immediately when no more
root marking tasks were available. However, it simplifies the code and
unifies these code paths.
This has negligible effect on the go1 benchmarks. It slightly slows
down the garbage benchmark, possibly by making GC run slightly more
frequently.
name old time/op new time/op delta
XBenchGarbage-12 5.10ms ± 1% 5.24ms ± 1% +2.87% (p=0.000 n=18+18)
name old time/op new time/op delta
BinaryTree17-12 3.25s ± 3% 3.20s ± 5% -1.57% (p=0.013 n=20+20)
Fannkuch11-12 2.45s ± 1% 2.46s ± 1% +0.38% (p=0.019 n=20+18)
FmtFprintfEmpty-12 49.7ns ± 3% 49.9ns ± 4% ~ (p=0.851 n=19+20)
FmtFprintfString-12 170ns ± 2% 170ns ± 1% ~ (p=0.775 n=20+19)
FmtFprintfInt-12 161ns ± 1% 160ns ± 1% -0.78% (p=0.000 n=19+18)
FmtFprintfIntInt-12 267ns ± 1% 270ns ± 1% +1.04% (p=0.000 n=19+19)
FmtFprintfPrefixedInt-12 238ns ± 2% 238ns ± 1% ~ (p=0.133 n=18+19)
FmtFprintfFloat-12 311ns ± 1% 310ns ± 2% -0.35% (p=0.023 n=20+19)
FmtManyArgs-12 1.08µs ± 1% 1.06µs ± 1% -2.31% (p=0.000 n=20+20)
GobDecode-12 8.65ms ± 1% 8.63ms ± 1% ~ (p=0.377 n=18+20)
GobEncode-12 6.49ms ± 1% 6.52ms ± 1% +0.37% (p=0.015 n=20+20)
Gzip-12 319ms ± 3% 318ms ± 1% ~ (p=0.975 n=19+17)
Gunzip-12 41.9ms ± 1% 42.1ms ± 2% +0.65% (p=0.004 n=19+20)
HTTPClientServer-12 61.7µs ± 1% 62.6µs ± 1% +1.40% (p=0.000 n=18+20)
JSONEncode-12 16.8ms ± 1% 16.9ms ± 1% ~ (p=0.239 n=20+18)
JSONDecode-12 58.4ms ± 1% 60.7ms ± 1% +3.85% (p=0.000 n=19+20)
Mandelbrot200-12 3.86ms ± 0% 3.86ms ± 1% ~ (p=0.092 n=18+19)
GoParse-12 3.75ms ± 2% 3.75ms ± 2% ~ (p=0.708 n=19+20)
RegexpMatchEasy0_32-12 100ns ± 1% 100ns ± 2% +0.60% (p=0.010 n=17+20)
RegexpMatchEasy0_1K-12 341ns ± 1% 342ns ± 2% ~ (p=0.203 n=20+19)
RegexpMatchEasy1_32-12 82.5ns ± 2% 83.2ns ± 2% +0.83% (p=0.007 n=19+19)
RegexpMatchEasy1_1K-12 495ns ± 1% 495ns ± 2% ~ (p=0.970 n=19+18)
RegexpMatchMedium_32-12 130ns ± 2% 130ns ± 2% +0.59% (p=0.039 n=19+20)
RegexpMatchMedium_1K-12 39.2µs ± 1% 39.3µs ± 1% ~ (p=0.214 n=18+18)
RegexpMatchHard_32-12 2.03µs ± 2% 2.02µs ± 1% ~ (p=0.166 n=18+19)
RegexpMatchHard_1K-12 61.0µs ± 1% 60.9µs ± 1% ~ (p=0.169 n=20+18)
Revcomp-12 533ms ± 1% 535ms ± 1% ~ (p=0.071 n=19+17)
Template-12 68.1ms ± 2% 73.0ms ± 1% +7.26% (p=0.000 n=19+20)
TimeParse-12 355ns ± 2% 356ns ± 2% ~ (p=0.530 n=19+20)
TimeFormat-12 357ns ± 2% 347ns ± 1% -2.59% (p=0.000 n=20+19)
[Geo mean] 62.1µs 62.3µs +0.31%
name old speed new speed delta
GobDecode-12 88.7MB/s ± 1% 88.9MB/s ± 1% ~ (p=0.377 n=18+20)
GobEncode-12 118MB/s ± 1% 118MB/s ± 1% -0.37% (p=0.015 n=20+20)
Gzip-12 60.9MB/s ± 3% 60.9MB/s ± 1% ~ (p=0.944 n=19+17)
Gunzip-12 464MB/s ± 1% 461MB/s ± 2% -0.64% (p=0.004 n=19+20)
JSONEncode-12 115MB/s ± 1% 115MB/s ± 1% ~ (p=0.236 n=20+18)
JSONDecode-12 33.2MB/s ± 1% 32.0MB/s ± 1% -3.71% (p=0.000 n=19+20)
GoParse-12 15.5MB/s ± 2% 15.5MB/s ± 2% ~ (p=0.702 n=19+20)
RegexpMatchEasy0_32-12 320MB/s ± 1% 318MB/s ± 2% ~ (p=0.094 n=18+20)
RegexpMatchEasy0_1K-12 3.00GB/s ± 1% 2.99GB/s ± 1% ~ (p=0.194 n=20+19)
RegexpMatchEasy1_32-12 388MB/s ± 2% 385MB/s ± 2% -0.83% (p=0.008 n=19+19)
RegexpMatchEasy1_1K-12 2.07GB/s ± 1% 2.07GB/s ± 1% ~ (p=0.964 n=19+18)
RegexpMatchMedium_32-12 7.68MB/s ± 1% 7.64MB/s ± 2% -0.57% (p=0.020 n=19+20)
RegexpMatchMedium_1K-12 26.1MB/s ± 1% 26.1MB/s ± 1% ~ (p=0.211 n=18+18)
RegexpMatchHard_32-12 15.8MB/s ± 1% 15.8MB/s ± 1% ~ (p=0.180 n=18+19)
RegexpMatchHard_1K-12 16.8MB/s ± 1% 16.8MB/s ± 2% ~ (p=0.236 n=20+19)
Revcomp-12 477MB/s ± 1% 475MB/s ± 1% ~ (p=0.071 n=19+17)
Template-12 28.5MB/s ± 2% 26.6MB/s ± 1% -6.77% (p=0.000 n=19+20)
[Geo mean] 100MB/s 99.0MB/s -0.82%
Change-Id: I875bf6ceb306d1ee2f470cabf88aa6ede27c47a0
Reviewed-on: https://go-review.googlesource.com/16059
Reviewed-by: Rick Hudson <rlh@golang.org>
Run-TryBot: Austin Clements <austin@google.com>
TryBot-Result: Gobot Gobot <gobot@golang.org>
We already have gcMarkWorkAvailable, but the check for GC mark work is
open-coded in several places. Generalize gcMarkWorkAvailable slightly
and replace these open-coded checks with calls to gcMarkWorkAvailable.
In addition to cleaning up the code, this puts us in a better position
to make this check slightly more complicated.
Change-Id: I1b29883300ecd82a1bf6be193e9b4ee96582a860
Reviewed-on: https://go-review.googlesource.com/16058
Reviewed-by: Rick Hudson <rlh@golang.org>
Run-TryBot: Austin Clements <austin@google.com>
TryBot-Result: Gobot Gobot <gobot@golang.org>
Abandon (but still support) the old numbering system.
GOTRACEBACK=none is old 0
GOTRACEBACK=single is the new behavior
GOTRACEBACK=all is old 1
GOTRACEBACK=system is old 2
GOTRACEBACK=crash is unchanged
See doc comment change in runtime1.go for details.
Filed #13107 to decide whether to change default back to GOTRACEBACK=all for Go 1.6 release.
If you run into programs where printing only the current goroutine omits
needed information, please add details in a comment on that issue.
Fixes#12366.
Change-Id: I82ca8b99b5d86dceb3f7102d38d2659d45dbe0db
Reviewed-on: https://go-review.googlesource.com/16512
Reviewed-by: Austin Clements <austin@google.com>
On ppc64x, the thread pointer, held in R13, points 0x7000 bytes past where
thread-local storage begins (presumably to maximize the amount of storage that
can be accessed with a 16-bit signed displacement). The relocations used to
indicate thread-local storage to the platform linker account for this, so to be
able to support external linking we need to change things so the linker applies
this offset instead of the runtime assembly.
Change-Id: I2556c249ab2d802cae62c44b2b4c5b44787d7059
Reviewed-on: https://go-review.googlesource.com/14233
Reviewed-by: Russ Cox <rsc@golang.org>
Reviewed-by: Austin Clements <austin@google.com>
This is needed to make external linking work.
Change-Id: I4cf7edb4ea318849cab92a697952f8745eed40c4
Reviewed-on: https://go-review.googlesource.com/14237
Reviewed-by: Ian Lance Taylor <iant@golang.org>
Android linker does not handle TLS for us. We set up the TLS slot
for g, as darwin/386,amd64 handle instead. This is disgusting and
fragile. We will eventually fix this ugly hack by taking advantage
of the recent TLS IE model implementation. (Instead of referencing
an GOT entry, make the code sequence look into the TLS variable that
holds the offset.)
The TLS slot for g in android/amd64 assumes a fixed offset from %fs.
See runtime/cgo/gcc_android_amd64.c for details.
For golang/go#10743
Change-Id: I1a3fc207946c665515f79026a56ea19134ede2dd
Reviewed-on: https://go-review.googlesource.com/15991
Reviewed-by: David Crawshaw <crawshaw@golang.org>
In the Go signal handler on Plan 9, when a signal with
the _SigThrow flag is received, we call startpanic before
printing the stack trace.
The startpanic function calls systemstack which calls
startpanic_m. In the startpanic_m function, we call
allocmcache to allocate _g_.m.mcache. The problem is
that allocmcache calls nextSample, which does a floating
point operation to return a sampling point for heap profiling.
However, Plan 9 doesn't support floating point in the
signal handler.
This change adds a new function nextSampleNoFP, only
called when in the Plan 9 signal handler, which is
similar to nextSample, but avoids floating point.
Change-Id: Iaa30437aa0f7c8c84d40afbab7567ad3bd5ea2de
Reviewed-on: https://go-review.googlesource.com/16307
Reviewed-by: Brad Fitzpatrick <bradfitz@golang.org>
Reviewed-by: Ian Lance Taylor <iant@golang.org>
The dynamic linker on linux/386 stores the address of the vsyscall helper at a
fixed offset from the %gs register on linux/386 for easy access from PIC code.
Change-Id: I635305cfecceef2289985d62e676e16810ed6b94
Reviewed-on: https://go-review.googlesource.com/16346
Reviewed-by: Ian Lance Taylor <iant@golang.org>
arena_{start,used,end} are already uintptr, so no need to convert them
to uintptr, much less to convert them to unsafe.Pointer and then to
uintptr. No binary change to pkg/linux_amd64/runtime.a.
Change-Id: Ia4232ed2a724c44fde7eba403c5fe8e6dccaa879
Reviewed-on: https://go-review.googlesource.com/16339
Reviewed-by: Brad Fitzpatrick <bradfitz@golang.org>
Run-TryBot: Brad Fitzpatrick <bradfitz@golang.org>
Implement an abort note on Plan 9, as an
equivalent of the SIGABRT signal on other
operating systems.
Updates #11975.
Change-Id: I010c9b10f2fbd2471aacd1d073368d975a2f0592
Reviewed-on: https://go-review.googlesource.com/16300
Reviewed-by: Brad Fitzpatrick <bradfitz@golang.org>
Run-TryBot: David du Colombier <0intro@gmail.com>
TryBot-Result: Gobot Gobot <gobot@golang.org>
When a new tiny block is allocated because we're allocating an object
that won't fit into the current block, mallocgc saves the new block if
it has more space leftover than the old block. However, the logic for
this was subtly broken in golang.org/cl/2814, resulting in never
saving (or consequently reusing) a tiny block.
Change-Id: Ib5f6769451fb82877ddeefe75dfe79ed4a04fd40
Reviewed-on: https://go-review.googlesource.com/16330
Run-TryBot: Matthew Dempsky <mdempsky@google.com>
TryBot-Result: Gobot Gobot <gobot@golang.org>
Reviewed-by: Ian Lance Taylor <iant@golang.org>
I went looking for an arm system whose stacks are by default smaller
than 64KB. In fact the smallest common linux target I could find was
Android, which like iOS uses 1MB stacks.
Fixes#11873
Change-Id: Ieeb66ad095b3da18d47ba21360ea75152a4107c6
Reviewed-on: https://go-review.googlesource.com/14602
Reviewed-by: Michael Hudson-Doyle <michael.hudson@canonical.com>
Reviewed-by: Minux Ma <minux@golang.org>
This copies the change from CL 16158 (applied as
22d4c8bf13).
Updates #13013
Change-Id: Id7d02e63d92806f06a4e064a91b2fb6574fe385f
Reviewed-on: https://go-review.googlesource.com/16291
Reviewed-by: Minux Ma <minux@golang.org>
Run-TryBot: Minux Ma <minux@golang.org>
TryBot-Result: Gobot Gobot <gobot@golang.org>
Modified GOSSA{HASH.PKG} environment variable filters to
make it easier to make/run with all SSA for testing.
Disable attempts at SSA for architectures that are not
amd64 (avoid spurious errors/unimplementeds.)
Removed easy out for unimplemented features.
Add convert op for proper liveness in presence of uintptr
to/from unsafe.Pointer conversions.
Tweaked stack sizes to get a pass on windows;
1024 instead 768, was observed to pass at least once.
Change-Id: Ida3800afcda67d529e3b1cf48ca4a3f0fa48b2c5
Reviewed-on: https://go-review.googlesource.com/16201
Reviewed-by: Keith Randall <khr@golang.org>
Run-TryBot: David Chase <drchase@google.com>
This CL introduces a new mSpanList type to replace the empty mspan
variables that were previously used as list heads.
To be type safe, the previous circular linked list data structure is
now a tail queue instead. One complication of this is
mSpanList_Remove needs to know the list a span is being removed from,
but this appears to be computable in all circumstances.
As a temporary sanity check, mSpanList_Insert and mSpanList_InsertBack
record the list that an mspan has been inserted into so that
mSpanList_Remove can verify that the correct list was specified.
Whereas mspan is 112 bytes on amd64, mSpanList is only 16 bytes. This
shrinks the size of mheap from 50216 bytes to 12584 bytes.
Change-Id: I8146364753dbc3b4ab120afbb9c7b8740653c216
Reviewed-on: https://go-review.googlesource.com/15906
Run-TryBot: Matthew Dempsky <mdempsky@google.com>
Reviewed-by: Austin Clements <austin@google.com>
It's never used as a *byte anyway, so might as well just make it an
unsafe.Pointer instead.
Change-Id: I68ee418781ab2fc574eeac0498f2515b5561b7a8
Reviewed-on: https://go-review.googlesource.com/16175
Run-TryBot: Matthew Dempsky <mdempsky@google.com>
TryBot-Result: Gobot Gobot <gobot@golang.org>
Reviewed-by: Ian Lance Taylor <iant@golang.org>
Reduces the size of m by ~8% on linux/amd64 (1040 bytes -> 960 bytes).
There are also windows-specific fields, but they're currently
referenced in OS-independent source files (but only when
GOOS=="windows").
Change-Id: I13e1471ff585ccced1271f74209f8ed6df14c202
Reviewed-on: https://go-review.googlesource.com/16173
Run-TryBot: Matthew Dempsky <mdempsky@google.com>
TryBot-Result: Gobot Gobot <gobot@golang.org>
Reviewed-by: Ian Lance Taylor <iant@golang.org>
Change compiler-invoked interface functions to directly take
iface/eface parameters instead of fInterface/interface{} to avoid
needing to always convert.
For the handful of functions that legitimately need to take an
interface{} parameter, add efaceOf to type-safely convert *interface{}
to *eface.
Change-Id: I8928761a12fd3c771394f36adf93d3006a9fcf39
Reviewed-on: https://go-review.googlesource.com/16166
Run-TryBot: Matthew Dempsky <mdempsky@google.com>
TryBot-Result: Gobot Gobot <gobot@golang.org>
Reviewed-by: Ian Lance Taylor <iant@golang.org>
Add explicit memory sanitizer instrumentation to the runtime and syscall
packages. The compiler does not instrument the runtime package. It
does instrument the syscall package, but we need to add a couple of
cases that it can't see.
Change-Id: I2d66073f713fe67e33a6720460d2bb8f72f31394
Reviewed-on: https://go-review.googlesource.com/16164
Reviewed-by: David Crawshaw <crawshaw@golang.org>
Allows removing a few gratuitous unsafe.Pointer conversions and
parallels the type of reflect.funcType's in and out fields ([]*rtype).
Change-Id: Ie5ca230a94407301a854dfd8782a3180d5054bc4
Reviewed-on: https://go-review.googlesource.com/16163
Run-TryBot: Matthew Dempsky <mdempsky@google.com>
TryBot-Result: Gobot Gobot <gobot@golang.org>
Reviewed-by: Ian Lance Taylor <iant@golang.org>
