NetBSD's semaphore implementation is derived from OpenBSD's, but has
subsequently diverged due to cleanups that were only applied to the
latter (https://golang.org/cl/137960043, https://golang.org/cl/5563).
This CL applies analogous cleanups for NetBSD.
Notably, we can also remove the scary NetBSD deadlock warning.
NetBSD's manual pages document that lwp_unpark on a not-yet-parked LWP
will cause that LWP's next lwp_park system call to return immediately,
so there's no race hazard.
Change-Id: Ib06844c420d2496ac289748eba13eb4700bbbbb2
Reviewed-on: https://go-review.googlesource.com/5564
Reviewed-by: Dmitry Vyukov <dvyukov@google.com>
Reviewed-by: Joel Sing <jsing@google.com>
(gdb) p x
Python Exception <class 'gdb.error'> There is no member named b.:
$2 = map[string]string
->
(gdb) p x
$1 = map[string]string = {["shane"] = "hansen"}
Change-Id: I874d02a029f2ac9afc5ab666afb65760ec2c3177
Reviewed-on: https://go-review.googlesource.com/5522
Reviewed-by: Ian Lance Taylor <iant@golang.org>
OpenBSD's thrsleep system call includes an "abort" parameter, which
specifies a memory address to be tested after being registered on the
sleep channel (i.e., capable of being woken up by thrwakeup). By
passing a pointer to waitsemacount for this parameter, we avoid race
conditions without needing a lock. Instead we just need to use
atomicload, cas, and xadd to mutate the semaphore count.
Change-Id: If9f2ab7cfd682da217f9912783cadea7e72283a8
Reviewed-on: https://go-review.googlesource.com/5563
Reviewed-by: Dmitry Vyukov <dvyukov@google.com>
Reviewed-by: Joel Sing <jsing@google.com>
When GODEBUG=gctrace=2 two gcs are preformed. During the first gc
the stack scan sets the g's gcscanvalid and gcworkdone flags to true
indicating that the stacks have to be scanned and do not need to
be rescanned. These need to be reset to false for the second GC so the
stacks are rescanned, otherwise if the only pointer to an object is
on the stack it will not be discovered and the object will be freed.
Typically this will include the object that was just allocated in
the mallocgc call that initiated the GC.
Change-Id: Ic25163f4689905fd810c90abfca777324005c02f
Reviewed-on: https://go-review.googlesource.com/5861
Reviewed-by: Russ Cox <rsc@golang.org>
Currently sync.Mutex is fully cooperative. That is, once contention is discovered,
the goroutine calls into scheduler. This is suboptimal as the resource can become
free soon after (especially if critical sections are short). Server software
usually runs at ~~50% CPU utilization, that is, switching to other goroutines
is not necessary profitable.
This change adds limited active spinning to sync.Mutex if:
1. running on a multicore machine and
2. GOMAXPROCS>1 and
3. there is at least one other running P and
4. local runq is empty.
As opposed to runtime mutex we don't do passive spinning,
because there can be work on global runq on on other Ps.
benchmark old ns/op new ns/op delta
BenchmarkMutexNoSpin 1271 1272 +0.08%
BenchmarkMutexNoSpin-2 702 683 -2.71%
BenchmarkMutexNoSpin-4 377 372 -1.33%
BenchmarkMutexNoSpin-8 197 190 -3.55%
BenchmarkMutexNoSpin-16 131 122 -6.87%
BenchmarkMutexNoSpin-32 170 164 -3.53%
BenchmarkMutexSpin 4724 4728 +0.08%
BenchmarkMutexSpin-2 2501 2491 -0.40%
BenchmarkMutexSpin-4 1330 1325 -0.38%
BenchmarkMutexSpin-8 684 684 +0.00%
BenchmarkMutexSpin-16 414 372 -10.14%
BenchmarkMutexSpin-32 559 469 -16.10%
BenchmarkMutex 19.1 19.1 +0.00%
BenchmarkMutex-2 81.6 54.3 -33.46%
BenchmarkMutex-4 143 100 -30.07%
BenchmarkMutex-8 154 156 +1.30%
BenchmarkMutex-16 140 159 +13.57%
BenchmarkMutex-32 141 163 +15.60%
BenchmarkMutexSlack 33.3 31.2 -6.31%
BenchmarkMutexSlack-2 122 97.7 -19.92%
BenchmarkMutexSlack-4 168 158 -5.95%
BenchmarkMutexSlack-8 152 158 +3.95%
BenchmarkMutexSlack-16 140 159 +13.57%
BenchmarkMutexSlack-32 146 162 +10.96%
BenchmarkMutexWork 154 154 +0.00%
BenchmarkMutexWork-2 89.2 89.9 +0.78%
BenchmarkMutexWork-4 139 86.1 -38.06%
BenchmarkMutexWork-8 177 162 -8.47%
BenchmarkMutexWork-16 170 173 +1.76%
BenchmarkMutexWork-32 176 176 +0.00%
BenchmarkMutexWorkSlack 160 160 +0.00%
BenchmarkMutexWorkSlack-2 103 99.1 -3.79%
BenchmarkMutexWorkSlack-4 155 148 -4.52%
BenchmarkMutexWorkSlack-8 176 170 -3.41%
BenchmarkMutexWorkSlack-16 170 173 +1.76%
BenchmarkMutexWorkSlack-32 175 176 +0.57%
"No work" benchmarks are not very interesting (BenchmarkMutex and
BenchmarkMutexSlack), as they are absolutely not realistic.
Fixes#8889
Change-Id: I6f14f42af1fa48f73a776fdd11f0af6dd2bb428b
Reviewed-on: https://go-review.googlesource.com/5430
Reviewed-by: Rick Hudson <rlh@golang.org>
Run-TryBot: Dmitry Vyukov <dvyukov@google.com>
This change deletes the C implementations of
the Go compiler and assembler from the master branch.
The Go implementations are a bit slower right now,
due mainly to garbage generated by taking addresses
of stack variables all over the place (it was C code,
after all). That will be cleaned up (mechanically) over the
next week or so, and things will get faster.
Change-Id: I66b2b3477aec8835f9960d0798f5752dcd98d08f
The slow path of heapBitsForObjects somewhat subtly assumes that the
pointer will not point to the first word of the object and will round
the pointer wrong if this assumption is violated. This assumption is
safe because the fast path should always take care of this case, but
there's no benefit to making this assumption, it makes the code more
difficult to experiment with than necessary, and it's trivial to
eliminate.
Change-Id: Iedd336f7d529a27d3abeb83e77dfb32a285ea73a
Reviewed-on: https://go-review.googlesource.com/5636
Reviewed-by: Russ Cox <rsc@golang.org>
The routine mallocgc retrieves objects from freelists. Prefetch
the object that will be returned in the next call to mallocgc.
Experiments indicate that this produces a 1% improvement when using
prefetchnta and less when using prefetcht0, prefetcht1, or prefetcht2.
Benchmark numbers indicate a 1% improvement over no
prefetch, much less over prefetcht0, prefetcht1, and prefetcht2.
These numbers were for the garbage benchmark with MAXPROCS=4
no prefetch >> 5.96 / 5.77 / 5.89
prefetcht0(uintptr(v.ptr().next)) >> 5.88 / 6.17 / 5.84
prefetcht1(uintptr(v.ptr().next)) >> 5.88 / 5.89 / 5.91
prefetcht2(uintptr(v.ptr().next)) >> 5.87 / 6.47 / 5.92
prefetchnta(uintptr(v.ptr().next)) >> 5.72 / 5.84 / 5.85
Change-Id: I54e07172081cccb097d5b5ce8789d74daa055ed9
Reviewed-on: https://go-review.googlesource.com/5350
Reviewed-by: Dmitry Vyukov <dvyukov@google.com>
Reviewed-by: Austin Clements <austin@google.com>
Makes them compatible with the new asm.
Applied mechanically from vet diagnostics.
Manual edits: the names for arguments in time·now(SB) in runtime/sys_*_arm.s.
Change-Id: Ib295390d9509d306afc67714e3f50dc832256625
Reviewed-on: https://go-review.googlesource.com/5576
Run-TryBot: Russ Cox <rsc@golang.org>
Reviewed-by: Rob Pike <r@golang.org>
With a trivial Golang-built program loaded in gdb-7.8.90.20150214-7.fc23.x86_64
I get this error:
(gdb) source ./src/runtime/runtime-gdb.py
Loading Go Runtime support.
Traceback (most recent call last):
File "./src/runtime/runtime-gdb.py", line 230, in <module>
_rctp_type = gdb.lookup_type("struct reflect.rtype").pointer()
gdb.error: No struct type named reflect.rtype.
(gdb) q
No matter if this struct should or should not be in every Golang-built binary
this change should fix that with no disadvantages.
Change-Id: I0c490d3c9bbe93c65a2183b41bfbdc0c0f405bd1
Reviewed-on: https://go-review.googlesource.com/5521
Reviewed-by: Ian Lance Taylor <iant@golang.org>
Trace command allows to visualize and analyze traces.
Run as:
$ go tool trace binary trace.file
The commands opens web browser with the main page,
which contains links for trace visualization,
blocking profiler, network IO profiler and per-goroutine
traces.
Also move trace parser from runtime/pprof/trace_parser_test.go
to internal/trace/parser.go, so that it can be shared between
tests and the command.
Change-Id: Ic97ed59ad6e4c7e1dc9eca5e979701a2b4aed7cf
Reviewed-on: https://go-review.googlesource.com/3601
Reviewed-by: Andrew Gerrand <adg@golang.org>
Restores stack traces in the android/arm builder.
Change-Id: If637aa2ed6f8886126b77cf9cc8a0535ec7c4369
Reviewed-on: https://go-review.googlesource.com/5453
Reviewed-by: Hyang-Ah Hana Kim <hyangah@gmail.com>
In most cases we pass return PC to race detector,
and race runtime subtracts one from them.
However, in manual instrumentation in runtime
we pass function start PC to race runtime.
Race runtime can't distinguish these cases
and so it does not subtract one from top PC.
This leads to bogus line numbers in some cases.
Make it consistent and always pass what looks
like a return PC, so that race runtime can
subtract one and still get PC in the same function.
Also delete two unused functions.
Update #8053
Change-Id: I4242dec5e055e460c9a8990eaca1d085ae240ed2
Reviewed-on: https://go-review.googlesource.com/4902
Reviewed-by: Ian Lance Taylor <iant@golang.org>
This is a nice split but more importantly it provides a better
way to fit the checkmark phase into the sequencing.
Also factor out common span copying into gcSpanCopy.
Change-Id: Ia058644974e4ed4ac3cf4b017a3446eb2284d053
Reviewed-on: https://go-review.googlesource.com/5333
Reviewed-by: Austin Clements <austin@google.com>
The loop made more sense when gc_m was not its own function.
Change-Id: I71a7f21d777e69c1924e3b534c507476daa4dfdd
Reviewed-on: https://go-review.googlesource.com/5332
Reviewed-by: Austin Clements <austin@google.com>
See the following issue for context:
https://github.com/golang/go/issues/9729#issuecomment-74648287
In short, RDTSC can produce skewed results without preceding LFENCE/MFENCE.
Information on this matter is very scrappy in the internet.
But this is what linux kernel does (see rdtsc_barrier).
It also fixes the test program on my machine.
Update #9729
Change-Id: I3c1ffbf129fdfdd388bd5b7911b392b319248e68
Reviewed-on: https://go-review.googlesource.com/5033
Reviewed-by: Ian Lance Taylor <iant@golang.org>
Fix many incorrect FP references and a few other details.
Some errors remain, especially in vlop, but fixing them requires semantics. For another day.
Change-Id: Ib769fb519b465e79fc08d004a51acc5644e8b259
Reviewed-on: https://go-review.googlesource.com/5288
Reviewed-by: Russ Cox <rsc@golang.org>
That is, I accidentally dropped this change of Austin's
when preparing my CL. I blame Git.
Change-Id: I9dd772c84edefad96c4b16785fdd2dea04a4a0d6
Reviewed-on: https://go-review.googlesource.com/5320
Reviewed-by: Austin Clements <austin@google.com>
Move code from malloc1.go, malloc2.go, mem.go, mgc0.go into
appropriate locations.
Factor mgc.go into mgc.go, mgcmark.go, mgcsweep.go, mstats.go.
A lot of this code was in certain files because the right place was in
a C file but it was written in Go, or vice versa. This is one step toward
making things actually well-organized again.
Change-Id: I6741deb88a7cfb1c17ffe0bcca3989e10207968f
Reviewed-on: https://go-review.googlesource.com/5300
Reviewed-by: Austin Clements <austin@google.com>
Reviewed-by: Rick Hudson <rlh@golang.org>
Until recently, struct workbuf had only lfnode and uintptr fields
before the obj array to make it convenient to compute the size of the
obj array. It slowly grew more fields until this became inconvenient
enough that it was restructured to make the size computation easy.
Now the size computation doesn't care what the field types are, so
switch to more natural types.
Change-Id: I966140ba7ebb4aeb41d5c66d9d2a3bdc17dd4bcf
Reviewed-on: https://go-review.googlesource.com/5262
Reviewed-by: Russ Cox <rsc@golang.org>
This converts the garbage collector from directly manipulating work
buffers to using the new gcWork abstraction.
The previous management of work buffers was rather ad hoc. As a
result, switching to the gcWork abstraction changes many details of
work buffer management.
If greyobject fills a work buffer, it can now pull from work.partial
in addition to work.empty.
Previously, gcDrain started with a partial or empty work buffer and
fetched an empty work buffer if it filled its current buffer (in
greyobject). Now, gcDrain starts with a full work buffer and fetches
an partial or empty work buffer if it fills its current buffer (in
greyobject). The original behavior was bad because gcDrain would
immediately drop the empty work buffer returned by greyobject and
fetch a full work buffer, which greyobject was likely to immediately
overflow, fetching another empty work buffer, etc. The new behavior
isn't great at the start because greyobject is likely to immediately
overflow the full buffer, but the steady-state behavior should be more
stable. Both before and after this change, gcDrain fetches a full
work buffer if it drains its current buffer. Basically all of these
choices are bad; the right answer is to use a dual work buffer scheme.
Previously, shade always fetched a work buffer (though usually from
m.currentwbuf), even if the object was already marked. Now it only
fetches a work buffer if it actually greys an object.
Change-Id: I8b880ed660eb63135236fa5d5678f0c1c041881f
Reviewed-on: https://go-review.googlesource.com/5232
Reviewed-by: Russ Cox <rsc@golang.org>
Reviewed-by: Rick Hudson <rlh@golang.org>
This introduces a producer/consumer abstraction for GC work pointers
that internally handles the details of filling, draining, and
shuffling work buffers.
In addition to simplifying the GC code, this should make it easy for
us to change how we use work buffers, including cleaning up how we use
the work.partial queue, reintroducing a FIFO lookahead cache, adding
prefetching, and using dual buffers to avoid flapping.
This commit doesn't change any existing code. The following commit
will switch the garbage collector from explicit workbuf manipulation
to gcWork.
Change-Id: Ifbfe5fff45bf0362d6d7c3cecb061f0c9874077d
Reviewed-on: https://go-review.googlesource.com/5231
Reviewed-by: Russ Cox <rsc@golang.org>
Reviewed-by: Rick Hudson <rlh@golang.org>
References to FP must now have a symbol.
Change-Id: I3f06b99cc48cbd4ccd6f23f2e4b0830af40f7f3d
Reviewed-on: https://go-review.googlesource.com/5281
Reviewed-by: Russ Cox <rsc@golang.org>
Nit. There's no reason to take a uintptr and doing so just requires
casts in annoying places.
Change-Id: Ifeb9638c6d94eae619c490930cf724cc315680ba
Reviewed-on: https://go-review.googlesource.com/5230
Reviewed-by: Russ Cox <rsc@golang.org>
Require a name to be specified when referencing the pseudo-stack.
If you want a real stack offset, use the hardware stack pointer (e.g.,
R13 on arm), not SP.
Fix affected assembly files.
Change-Id: If3545f187a43cdda4acc892000038ec25901132a
Reviewed-on: https://go-review.googlesource.com/5120
Run-TryBot: Rob Pike <r@golang.org>
Reviewed-by: Russ Cox <rsc@golang.org>
Reviewed-by: Dave Cheney <dave@cheney.net>
Apparently when ARM stops at a GDB breakpoint, it appears to be in
syscall.Syscall. The "info goroutines" test expected it to be in a
runtime function. Since this isn't fundamental to the test, simply
tweak the test's regexp to make sure "info goroutines" prints some
running goroutine with an active M, but don't require it to be in any
particular function.
Change-Id: Iba2618b46d3dc49cef62ffb72484b83ea7b0317d
Reviewed-on: https://go-review.googlesource.com/5060
Reviewed-by: Dave Cheney <dave@cheney.net>
All of the other memory-related source files start with "m". Keep up
the tradition.
Change-Id: Idd88fdbf2a1453374fa12109b949b1c4d149a4f8
Reviewed-on: https://go-review.googlesource.com/4853
Reviewed-by: Minux Ma <minux@golang.org>
Rather than reaching in to slices directly in the slice pretty
printer, use the newly introduced SliceValue wrapper.
Change-Id: Ibb25f8c618c2ffb3fe1a8dd044bb9a6a085df5b7
Reviewed-on: https://go-review.googlesource.com/4936
Reviewed-by: Minux Ma <minux@golang.org>
"info goroutines" is failing because it hasn't kept up with changes in
the 1.5 runtime. This fixes three issues preventing "info goroutines"
from working. allg is no longer a linked list, so switch to using the
allgs slice. The g struct's 'status' field is now called
'atomicstatus', so rename uses of 'status'. Finally, this was trying
to parse str(pc) as an int, but str(pc) can return symbolic
information after the raw hex value; fix this by stripping everything
after the first space.
This also adds a test for "info goroutines" to runtime-gdb_test, which
was previously quite skeletal.
Change-Id: I8ad83ee8640891cdd88ecd28dad31ed9b5833b7a
Reviewed-on: https://go-review.googlesource.com/4935
Reviewed-by: Minux Ma <minux@golang.org>
R15 is the real register. PC is a pseudo-register that we are making
illegal in this context as part of the grand assembly unification.
Change-Id: Ie0ea38ce7ef4d2cf4fcbe23b851a570fd312ce8d
Reviewed-on: https://go-review.googlesource.com/4966
Reviewed-by: Minux Ma <minux@golang.org>
There is currently no way to ignore signals using the os/signal package.
It is possible to catch a signal and do nothing but this is not the same
as ignoring it. The new function Ignore allows a set of signals to be
ignored. The new function Reset allows the initial handlers for a set of
signals to be restored.
Fixes#5572
Change-Id: I5c0f07956971e3a9ff9b9d9631e6e3a08c20df15
Reviewed-on: https://go-review.googlesource.com/3580
Reviewed-by: Ian Lance Taylor <iant@golang.org>
Change 85e7bee introduced a bug:
it marks map buckets as noscan when key and val do not contain pointers.
However, buckets with large/outline key or val do contain pointers.
This change takes key/val size into consideration when
marking buckets as noscan.
Change-Id: I7172a0df482657be39faa59e2579dd9f209cb54d
Reviewed-on: https://go-review.googlesource.com/4901
Reviewed-by: Keith Randall <khr@golang.org>
Several .s files for ARM had several properties the new assembler will not support.
These include:
- mentioning SP or PC as a hardware register
These are always pseudo-registers except that in some contexts
they're not, and it's confusing because the context should not affect
which register you mean. Change the references to the hardware
registers to be explicit: R13 for SP, R15 for PC.
- constant creation using assignment
The files say a=b when they could instead say #define a b.
There is no reason to have both mechanisms.
- R(0) to refer to R0.
Some macros use this to a great extent. Again, it's easy just to
use a #define to rename a register.
Change-Id: I002335ace8e876c5b63c71c2560533eb835346d2
Reviewed-on: https://go-review.googlesource.com/4822
Reviewed-by: Dave Cheney <dave@cheney.net>
MOVQ RARG0, 0(SP) smashes exactly what was saved by PUSHQ R15.
This code managed to work somehow with the current race runtime,
but corrupts caller arguments with new race runtime that I am testing.
Change-Id: I9ffe8b5eee86451db36e99dbf4d11f320192e576
Reviewed-on: https://go-review.googlesource.com/4810
Reviewed-by: Keith Randall <khr@golang.org>
New race runtime is more scrupulous about env flags format.
Change-Id: I2828bc737a8be3feae5288ccf034c52883f224d8
Reviewed-on: https://go-review.googlesource.com/4811
Reviewed-by: Brad Fitzpatrick <bradfitz@golang.org>
drainworkbuf is now gcDrain, since it drains until there's
nothing left to drain. drainobjects is now gcDrainN because it's
the bounded equivalent to gcDrain.
The new names use the Go camel case convention because we have to
start somewhere. The "gc" prefix is because we don't have runtime
packages yet and just "drain" is too ambiguous.
Change-Id: I88dbdf32e8ce4ce6c3b7e1f234664be9b76cb8fd
Reviewed-on: https://go-review.googlesource.com/4785
Reviewed-by: Russ Cox <rsc@golang.org>
Reviewed-by: Rick Hudson <rlh@golang.org>
All calls to drainworkbuf now pass true for this argument, so remove
the argument and update the documentation to reflect the simplified
interface.
At a higher level, there are no longer any situations where we drain
"one wbuf" (though drainworkbuf didn't guarantee this anyway). We
either drain everything, or we drain a specific number of objects.
Change-Id: Ib7ee0fde56577eff64232ee1e711ec57c4361335
Reviewed-on: https://go-review.googlesource.com/4784
Reviewed-by: Russ Cox <rsc@golang.org>
Reviewed-by: Rick Hudson <rlh@golang.org>
scanblock is only called during _GCscan and _GCmarktermination.
During _GCscan, scanblock didn't call drainworkbufs anyway. During
_GCmarktermination, there's really no point in draining some (largely
arbitrary) amount of work during the scanblock, since the GC is about
to drain everything anyway, so simply eliminate this case.
Change-Id: I7f3c59ce9186a83037c6f9e9b143181acd04c597
Reviewed-on: https://go-review.googlesource.com/4783
Reviewed-by: Russ Cox <rsc@golang.org>
We no longer ever call scanblock with b == 0.
Change-Id: I9b01da39595e0cc251668c24d58748d88f5f0792
Reviewed-on: https://go-review.googlesource.com/4782
Reviewed-by: Russ Cox <rsc@golang.org>
Reviewed-by: Rick Hudson <rlh@golang.org>
scanblock(0, 0, nil, nil) was just a confusing way of saying
wbuf = getpartialorempty()
drainworkbuf(wbuf, true)
Make drainworkbuf accept a nil workbuf and perform the
getpartialorempty itself and replace all uses of scanblock(0, 0, nil,
nil) with direct calls to drainworkbuf(nil, true).
Change-Id: I7002a2f8f3eaf6aa85bbf17ccc81d7288acfef1c
Reviewed-on: https://go-review.googlesource.com/4781
Reviewed-by: Russ Cox <rsc@golang.org>
Reviewed-by: Rick Hudson <rlh@golang.org>
Previously, scanblock called checknocurrentwbuf() after
drainworkbuf(). Move this call into drainworkbuf so that every return
path from drainworkbuf calls checknocurrentwbuf(). This is equivalent
to the previous code because scanblock was the only caller of
drainworkbuf.
Change-Id: I96ef2168c8aa169bfc4d368f296342fa0fbeafb4
Reviewed-on: https://go-review.googlesource.com/4780
Reviewed-by: Russ Cox <rsc@golang.org>
Reviewed-by: Rick Hudson <rlh@golang.org>
Currently we always create context objects for closures that capture variables.
However, it is completely unnecessary for direct calls of closures
(whether it is func()(), defer func()() or go func()()).
This change transforms any OCALLFUNC(OCLOSURE) to normal function call.
Closed variables become function arguments.
This transformation is especially beneficial for go func(),
because we do not need to allocate context object on heap.
But it makes direct closure calls a bit faster as well (see BenchmarkClosureCall).
On implementation level it required to introduce yet another compiler pass.
However, the pass iterates only over xtop, so it should not be an issue.
Transformation consists of two parts: closure transformation and call site
transformation. We can't run these parts on different sides of escape analysis,
because tree state is inconsistent. We can do both parts during typecheck,
we don't know how to capture variables and don't have call site.
We can't do both parts during walk of OCALLFUNC, because we can walk
OCLOSURE body earlier.
So now capturevars pass only decides how to capture variables
(this info is required for escape analysis). New transformclosure
pass, that runs just before order/walk, does all transformations
of a closure. And later walk of OCALLFUNC(OCLOSURE) transforms call site.
benchmark old ns/op new ns/op delta
BenchmarkClosureCall 4.89 3.09 -36.81%
BenchmarkCreateGoroutinesCapture 1634 1294 -20.81%
benchmark old allocs new allocs delta
BenchmarkCreateGoroutinesCapture 6 2 -66.67%
benchmark old bytes new bytes delta
BenchmarkCreateGoroutinesCapture 176 48 -72.73%
Change-Id: Ic85e1706e18c3235cc45b3c0c031a9c1cdb7a40e
Reviewed-on: https://go-review.googlesource.com/4050
Reviewed-by: Russ Cox <rsc@golang.org>
Consider an interface value i of type I and concrete value c of type C.
Prior to this CL, i==c was evaluated as
I(c) == i
Evaluating I(c) can allocate.
This CL changes the evaluation of i==c to
x, ok := i.(C); ok && x == c
The new generated code is shorter and does not allocate directly.
If C is small, as it is in every instance in the stdlib,
the new code also uses less stack space
and makes one runtime call instead of two.
If C is very large, the original implementation is used.
The cutoff for "very large" is 1<<16,
following the stack vs heap cutoff used elsewhere.
This kind of comparison occurs in 38 places in the stdlib,
mostly in the net and os packages.
benchmark old ns/op new ns/op delta
BenchmarkEqEfaceConcrete 29.5 7.92 -73.15%
BenchmarkEqIfaceConcrete 32.1 7.90 -75.39%
BenchmarkNeEfaceConcrete 29.9 7.90 -73.58%
BenchmarkNeIfaceConcrete 35.9 7.90 -77.99%
Fixes#9370.
Change-Id: I7c4555950bcd6406ee5c613be1f2128da2c9a2b7
Reviewed-on: https://go-review.googlesource.com/2096
Reviewed-by: Russ Cox <rsc@golang.org>
Run-TryBot: Josh Bleecher Snyder <josharian@gmail.com>
No code modifications.
This is in preparation for improving the wbuf abstraction.
Change-Id: I719543a345c34d079b7e39b251eccd5dd8a07826
Reviewed-on: https://go-review.googlesource.com/4710
Reviewed-by: Rick Hudson <rlh@golang.org>
Plan 9's sysFree has an optimization where if the object being freed
is the last object allocated, it will roll back the brk to allow the
memory to be reused by sysAlloc. However, it does not zero this
"returned" memory, so as a result, sysAlloc can return non-zeroed
memory after a sysFree. This leads to corruption because the runtime
assumes sysAlloc returns zeroed memory.
Fix this by zeroing the memory returned by sysFree.
Fixes#9846.
Change-Id: Id328c58236eb7c464b31ac1da376a0b757a5dc6a
Reviewed-on: https://go-review.googlesource.com/4700
Reviewed-by: Russ Cox <rsc@golang.org>
Reviewed-by: David du Colombier <0intro@gmail.com>
typedslicecopy is another write barrier that is not
understood by racewalk. It seems quite complex to handle it
in the compiler, so instead just instrument it in runtime.
Update #9796
Change-Id: I0eb6abf3a2cd2491a338fab5f7da22f01bf7e89b
Reviewed-on: https://go-review.googlesource.com/4370
Reviewed-by: Russ Cox <rsc@golang.org>
Support the following conversions in escape analysis:
[]rune("foo")
[]byte("foo")
string([]rune{})
If the result does not escape, allocate temp buffer on stack
and pass it to runtime functions.
Change-Id: I1d075907eab8b0109ad7ad1878104b02b3d5c690
Reviewed-on: https://go-review.googlesource.com/3590
Reviewed-by: Russ Cox <rsc@golang.org>
Add local workbufs to the m struct in order to reduce contention.
Add consistency checks for workbuf ownership.
Chain workbufs through call change to avoid swapping them
to and from the m struct.
Adjust the size of the workbuf so that the mutators can
more frequently pass modifications to the GC thus shifting
some work from the STW mark termination phase to the concurrent
mark phase.
Change-Id: I557b53af34ad9972265e0ed9f5996e52d548563d
Reviewed-on: https://go-review.googlesource.com/3972
Reviewed-by: Austin Clements <austin@google.com>
Fixes#9791
g.issystem flag setup races with other code wherever we set it.
Even if we set both in parent goroutine and in the system goroutine,
it is still possible that some other goroutine crashes
before the flag is set. We could pass issystem flag to newproc1,
but we start all goroutines with go nowadays.
Instead look at g.startpc to distinguish system goroutines (similar to topofstack).
Change-Id: Ia3467968dee27fa07d9fecedd4c2b00928f26645
Reviewed-on: https://go-review.googlesource.com/4113
Reviewed-by: Keith Randall <khr@golang.org>
Update #8832
This is probably not the root cause of the issue.
Resolve TODO about setting unusedsince on a wrong span.
Change-Id: I69c87e3d93cb025e3e6fa80a8cffba6ad6ad1395
Reviewed-on: https://go-review.googlesource.com/4390
Reviewed-by: Keith Randall <khr@golang.org>
Container symbols shouldn't be considered as functions in the functab.
Having them present probably messes up function lookup, as you might get
the descriptor of the container instead of the descriptor of the actual
function on the stack. It also messed up the findfunctab because these
entries caused off-by-one errors in how functab entries were counted.
Normal code is not affected - it only changes (& hopefully fixes) the
behavior for libraries linked as a unit, like:
net
runtime/cgo
runtime/race
Fixes#9804
Change-Id: I81e036e897571ac96567d59e1f1d7f058ca75e85
Reviewed-on: https://go-review.googlesource.com/4290
Reviewed-by: Russ Cox <rsc@golang.org>
This CL introduces new methods for 'context' type, so we can
manipulate its values in an architecture independent way.
Use new methods to replace both 386 and amd64 versions of
dosigprof with single piece of code.
There is more similar code to be converted in the following CLs.
Also remove os_windows_386.go and os_windows_amd64.go. These
contain unused functions.
Change-Id: I28f76aeb97f6e4249843d30d3d0c33fb233d3f7f
Reviewed-on: https://go-review.googlesource.com/2790
Reviewed-by: Minux Ma <minux@golang.org>
CL 2118 makes the assumption that all references to runtime.tlsg
should be accompanied by a declaration of runtime.tlsg if its type
should be a normal variable, instead of a placeholder for TLS
relocation.
Because if runtime.tlsg is not declared by the runtime package,
the type of runtime.tlsg will be zero, so fix the check in liblink
to look for 0 instead of STLSBSS (the type will be initialized by
cmd/ld, but cmd/ld doesn't run during assembly).
Change-Id: I691ac5c3faea902f8b9a0b963e781b22e7b269a7
Reviewed-on: https://go-review.googlesource.com/4030
Reviewed-by: David Crawshaw <crawshaw@golang.org>
This change is an implementation of the signal
runtime and os/signal package on Plan 9.
Contrary to Unix, on Plan 9 a signal is called
a note and is represented by a string.
For this reason, the sigsend and signal_recv
functions had to be reimplemented specifically
for Plan 9.
In order to reuse most of the code and internal
interface of the os/signal package, the note
strings are mapped to integers.
Thanks to Russ Cox for the early review.
Change-Id: I95836645efe21942bb1939f43f87fb3c0eaaef1a
Reviewed-on: https://go-review.googlesource.com/2164
Reviewed-by: Brad Fitzpatrick <bradfitz@golang.org>
Reviewed-by: Rob Pike <r@golang.org>
It turns out -iex argument is not supported by all gdb versions,
but as we need to add the auto-load safe path before loading the
inferior, test -iex support first and skip the test if it's not
available.
We should still update our builders though.
Change-Id: I355697de51baf12162ba6cb82f389dad93f93dc5
Reviewed-on: https://go-review.googlesource.com/4070
Reviewed-by: Ian Lance Taylor <iant@golang.org>
On some systems, gdb refuses to load Python plugin from arbitrary
paths, so we have to add $GOROOT/src/runtime to auto-load-safe-path
in the gdb script test.
Change-Id: Icc44baab8d04a65bd21ceac2ab8ddb13c8d083e8
Reviewed-on: https://go-review.googlesource.com/2905
Reviewed-by: Ian Lance Taylor <iant@golang.org>
Reviewed-by: Josh Bleecher Snyder <josharian@gmail.com>
eqstring does not need to check the length of the strings.
Other architectures were done in a separate commit.
While we're here, add a pointer equality check.
Change-Id: Id2c8616a03a7da7037c1e9ccd56a549fc952bd98
Reviewed-on: https://go-review.googlesource.com/3956
Reviewed-by: Keith Randall <khr@golang.org>
eqstring does not need to check the length of the strings.
6g
benchmark old ns/op new ns/op delta
BenchmarkCompareStringEqual 7.03 6.14 -12.66%
BenchmarkCompareStringIdentical 3.36 3.04 -9.52%
5g
benchmark old ns/op new ns/op delta
BenchmarkCompareStringEqual 238 232 -2.52%
BenchmarkCompareStringIdentical 90.8 80.7 -11.12%
The equivalent PPC changes are in a separate commit
because I don't have the hardware to test them.
Change-Id: I292874324b9bbd9d24f57a390cfff8b550cdd53c
Reviewed-on: https://go-review.googlesource.com/3955
Reviewed-by: Keith Randall <khr@golang.org>
Only documentation / comment changes. Update references to
point to golang.org permalinks or go.googlesource.com/go.
References in historical release notes under doc are left as is.
Change-Id: Icfc14e4998723e2c2d48f9877a91c5abef6794ea
Reviewed-on: https://go-review.googlesource.com/4060
Reviewed-by: Ian Lance Taylor <iant@golang.org>
In the old code, liblink, cmd/ld and runtime all have code determine
whether runtime.tlsg is an actual variable or a placeholder for TLS
relocation. This change consolidate them into one: the runtime/tls_arm.s
will ultimately determine the type of that variable.
Change-Id: I3b3f80791a1db4c2b7318f81a115972cd2237e43
Reviewed-on: https://go-review.googlesource.com/2118
Reviewed-by: David Crawshaw <crawshaw@golang.org>
Reviewed-by: Dave Cheney <dave@cheney.net>
In android-L, logging is done through the logd daemon.
If logd daemon is available, send logging to logd.
Otherwise, fallback to the legacy mechanism (/dev/log files).
This change adds access/socket/connect calls to interact with the logd.
Fixesgolang/go#9398.
Change-Id: I3c52b81b451f5862107d7c675f799fc85548486d
Reviewed-on: https://go-review.googlesource.com/3350
Reviewed-by: David Crawshaw <crawshaw@golang.org>
The unbounded list-based defer pool can grow infinitely.
This can happen if a goroutine routinely allocates a defer;
then blocks on one P; and then unblocked, scheduled and
frees the defer on another P.
The scenario was reported on golang-nuts list.
We've been here several times. Any unbounded local caches
are bad and grow to infinite size. This change introduces
central defer pool; local pools become fixed-size
with the only purpose of amortizing accesses to the
central pool.
Change-Id: Iadcfb113ccecf912e1b64afc07926f0de9de2248
Reviewed-on: https://go-review.googlesource.com/3741
Reviewed-by: Keith Randall <khr@golang.org>
Using benchmark from the issue:
benchmark old ns/op new ns/op delta
BenchmarkRangeStringCast 2162 1152 -46.72%
benchmark old allocs new allocs delta
BenchmarkRangeStringCast 1 0 -100.00%
Fixes#2204
Change-Id: I92c5edd2adca4a7b6fba00713a581bf49dc59afe
Reviewed-on: https://go-review.googlesource.com/3790
Reviewed-by: Keith Randall <khr@golang.org>
Before 3c0fee1, runtime.gogo was just long enough to align to 64 bytes
on OSs with short get_tls implementations and 80 bytes on OSs with
longer get_tls implementations (Windows, Solaris, and Plan 9).
3c0fee1 added a few instructions, which pushed it to 80 on most OSs,
including Windows and Plan 9, and 96 on Solaris.
Fixes#9770.
Change-Id: Ie84810657c14ab16dce9f0e0a932955251b0bf33
Reviewed-on: https://go-review.googlesource.com/3850
Reviewed-by: Alex Brainman <alex.brainman@gmail.com>
Use memprofilerate in GODEBUG instead of memprofrate to be
consistent with other uses.
Change-Id: Iaf6bd3b378b1fc45d36ecde32f3ad4e63ca1e86b
Reviewed-on: https://go-review.googlesource.com/3800
Reviewed-by: Ian Lance Taylor <iant@golang.org>
The overflow happens only with -gcflags="-N -l"
and can be reproduced with:
$ go test -gcflags="-N -l" -a -run=none net
runtime.cgocall: nosplit stack overflow
504 assumed on entry to runtime.cgocall
480 after runtime.cgocall uses 24
472 on entry to runtime.cgocall_errno
408 after runtime.cgocall_errno uses 64
400 on entry to runtime.exitsyscall
288 after runtime.exitsyscall uses 112
280 on entry to runtime.exitsyscallfast
152 after runtime.exitsyscallfast uses 128
144 on entry to runtime.writebarrierptr
88 after runtime.writebarrierptr uses 56
80 on entry to runtime.writebarrierptr_nostore1
24 after runtime.writebarrierptr_nostore1 uses 56
16 on entry to runtime.acquirem
-24 after runtime.acquirem uses 40
Move closure creation into separate function so that
frames of writebarrierptr_shadow and writebarrierptr_nostore1
are overlapped.
Fixes#9721
Change-Id: I40851f0786763ee964af34814edbc3e3d73cf4e7
Reviewed-on: https://go-review.googlesource.com/3418
Reviewed-by: Russ Cox <rsc@golang.org>
Currently race detector produces the following reports on pprof tests:
WARNING: DATA RACE
Read by goroutine 4:
runtime/pprof_test.TestTraceStartStop()
src/runtime/pprof/trace_test.go:38 +0x1da
testing.tRunner()
src/testing/testing.go:448 +0x13a
Previous write by goroutine 5:
bytes.(*Buffer).grow()
src/bytes/buffer.go:102 +0x190
bytes.(*Buffer).Write()
src/bytes/buffer.go:127 +0x75
runtime/pprof.func·002()
src/runtime/pprof/pprof.go:633 +0xae
Trace writer goroutine synchronizes with StopTrace
using trace.shutdownSema runtime semaphore.
But race detector does not see that synchronization
and so produces false reports.
Teach race detector about the synchronization.
Change-Id: I1219817325d4e16b423f29a0cbee94c929793881
Reviewed-on: https://go-review.googlesource.com/3746
Reviewed-by: Russ Cox <rsc@golang.org>
The test for the framepointer experiment flag is cheaper and more
branch-predictable than the other parts of this conditional, so move
it first. This is also more readable.
(Originally, the flag check required parsing the experiments string,
which is why it was done last. Now that flag is cached.)
Change-Id: I84e00fa7e939e9064f0fa0a4a6fe00576dd61457
Reviewed-on: https://go-review.googlesource.com/3782
Reviewed-by: Brad Fitzpatrick <bradfitz@golang.org>
Previously, we checked for a saved frame pointer by looking for a
2*ptrSize gap between the argument pointer and the locals pointer.
The intent of this check was to look for a two stack slot gap (caller
IP and saved frame pointer), but stack slots are regSize, not ptrSize.
Correct this by checking instead for a 2*regSize gap.
On most platforms, this made no difference because ptrSize==regSize.
However, on amd64p32 (nacl), the saved frame pointer check incorrectly
fired when there was no saved frame pointer because the one stack slot
for the caller IP left an 8 byte gap, which is 2*ptrSize (but not
2*regSize) on amd64p32.
Fixes#9760.
Change-Id: I6eedcf681fe5bf2bf924dde8a8f2d9860a4d758e
Reviewed-on: https://go-review.googlesource.com/3781
Reviewed-by: Brad Fitzpatrick <bradfitz@golang.org>
Add memprofrate as a value recognized in GODEBUG. The
value provided is used as the new setting for
runtime.MemProfileRate, allowing the user to
adjust memory profiling.
Change-Id: If129a247683263b11e2dd42473cf9b31280543d5
Reviewed-on: https://go-review.googlesource.com/3450
Reviewed-by: Ian Lance Taylor <iant@golang.org>
This adds a "framepointer" GOEXPERIMENT that that makes the amd64
toolchain maintain base pointer chains in the same way that gcc
-fno-omit-frame-pointer does. Go doesn't use these saved base
pointers, but this does enable external tools like Linux perf and
VTune to unwind Go stacks when collecting system-wide profiles.
This requires support in the compilers to not clobber BP, support in
liblink for generating the BP-saving function prologue and unwinding
epilogue, and support in the runtime to save BPs across preemption, to
skip saved BPs during stack unwinding and, and to adjust saved BPs
during stack moving.
As with other GOEXPERIMENTs, everything from the toolchain to the
runtime must be compiled with this experiment enabled. To do this,
run make.bash (or all.bash) with GOEXPERIMENT=framepointer.
Change-Id: I4024853beefb9539949e5ca381adfdd9cfada544
Reviewed-on: https://go-review.googlesource.com/2992
Reviewed-by: Russ Cox <rsc@golang.org>
Any place that clobbers BP in the runtime can potentially interfere
with frame pointer unwinding with GOEXPERIMENT=framepointer. This
change eliminates uses of BP in the runtime to address this problem.
We have spare registers everywhere this occurs, so there's no downside
to eliminating BP. Where possible, this uses the same new register as
the amd64p32 runtime, which doesn't use BP due to restrictions placed
on it by NaCL.
One nice side effect of this is that it will let perf/VTune unwind the
call stack even through a call to systemstack, which will let us get
really good call graphs from the garbage collector.
Change-Id: I0ffa14cb4dd2b613a7049b8ec59df37c52286212
Reviewed-on: https://go-review.googlesource.com/3390
Reviewed-by: Minux Ma <minux@golang.org>
Reviewed-by: Russ Cox <rsc@golang.org>
m.gcing has become overloaded to mean "don't preempt this g" in
general. Once the garbage collector is preemptible, the one thing it
*won't* mean is that we're in the garbage collector.
So, rename gcing to "preemptoff" and make it a string giving a reason
that preemption is disabled. gcing was never set to anything but 0 or
1, so we don't have to worry about there being a stack of reasons.
Change-Id: I4337c29e8e942e7aa4f106fc29597e1b5de4ef46
Reviewed-on: https://go-review.googlesource.com/3660
Reviewed-by: Russ Cox <rsc@golang.org>
