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>
The change 2096 removed unwanted allocations and a few noises in test
using AllocsPerRun. Now it's safe to enable this canary test on netpoll
hotpaths.
Change-Id: Icdbee813d81c1410a48ea9960d46447042976905
Reviewed-on: https://go-review.googlesource.com/5713
Reviewed-by: Dmitry Vyukov <dvyukov@google.com>
This check is expensive and adversely impacts startup times for some
servers with several, large RSA keys.
It was nice to have, but it's not really going to stop a targetted
attack and was never designed to – hopefully people's private keys
aren't attacker controlled!
Overall I think the feeling is that people would rather have the CPU
time back.
Fixes#6626.
Change-Id: I0143a58c9f22381116d4ca2a3bbba0d28575f3e5
Reviewed-on: https://go-review.googlesource.com/5641
Reviewed-by: Brad Fitzpatrick <bradfitz@golang.org>
Run-TryBot: Adam Langley <agl@golang.org>
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>
Ran rsc.io/grind rev 6f0e601 on the source files.
The cleanups move var declarations as close to the use
as possible, splitting disjoint uses of the var into separate
variables. They also remove dead code (especially in
func sudoaddable), which helps with the var moving.
There's more cleanup to come, but this alone cuts the
time spent compiling html/template on my 2013 MacBook Pro
from 3.1 seconds to 2.3 seconds.
Change-Id: I4de499f47b1dd47a560c310bbcde6b08d425cfd6
Reviewed-on: https://go-review.googlesource.com/5637
Reviewed-by: Rob Pike <r@golang.org>
Also stop building objwriter, which was only used by them.
Change-Id: Ia2353abd9426026a81a263cb46a72dd39c360ce4
Reviewed-on: https://go-review.googlesource.com/5634
Reviewed-by: Rob Pike <r@golang.org>
Convert using rsc.io/c2go rev a97ff47.
Notable changes:
- %% in format string now correctly preserved
- reintroduce "signal handler" to hide internal faults
after errors have been printed
Change-Id: Ic5a94f1c3a8015a9054e21c8969b52d964a36c45
Reviewed-on: https://go-review.googlesource.com/5633
Reviewed-by: Rob Pike <r@golang.org>
These don't work with the new compiler, because the
new compiler doesn't have the custom syntax errors
that I built for the old compiler. It will, just not yet.
(Issue #9968.)
Change-Id: I658f7dab2c7f855340a501f9ae4479c097b28cd3
Reviewed-on: https://go-review.googlesource.com/5632
Reviewed-by: Rob Pike <r@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>
The code concerning quoted-printable encoding (RFC 2045) and its
variant for MIME headers (RFC 2047) is currently spread in
mime/multipart and net/mail. It is also not exported.
This commit is the second step to fix that issue. It moves the
RFC 2047 encoding and decoding functions from net/mail to
internal/mime. The exported API is unchanged.
Updates #4943
Change-Id: I5f58aa58e74bbe4ec91b2e9b8c81921338053b00
Reviewed-on: https://go-review.googlesource.com/2101
Reviewed-by: Brad Fitzpatrick <bradfitz@golang.org>
We currently have only one supported darwin/arm device, a locked iOS
machine. It requires cgo binaries.
Change-Id: If36a152e6a743e4a58ea3470e62cccb742630a5d
Reviewed-on: https://go-review.googlesource.com/5443
Reviewed-by: Russ Cox <rsc@golang.org>
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>
This was supposed to be in the previous CL, but I forgot to 'git rw' it down.
Change-Id: Ia5e14ca2c7640f08abbbed1a777a6cf04d71d0e7
Reviewed-on: https://go-review.googlesource.com/5570
Reviewed-by: Russ Cox <rsc@golang.org>
The wildcard 'std' is defined in documentation to be all the packages
in the Go standard library. It has also historically matched commands
in the main repo, but as we implement core commands in Go, that
becomes problematic. We need a wildcard that means just the library,
and since 'std' is already documented to have that definition, make it so.
Add a new wildcard 'cmd' for the commands in the main repo ($GOROOT).
Commands that want both can say 'std cmd' (or 'cmd std') to get the
effect of the old 'std'.
Update make.bash etc to say both std and cmd most of the time.
Exception: in race.bash, do not install race-enabled versions of
the actual commands. This avoids trying to write binaries while
using them, but more importantly it avoids enabling the race
detector and its associated memory overhead for the already
memory-hungry compilers.
Change-Id: I26bb06cb13b636dfbe71a015ee0babeb270a0275
Reviewed-on: https://go-review.googlesource.com/5550
Run-TryBot: Russ Cox <rsc@golang.org>
Reviewed-by: Rob Pike <r@golang.org>
cpp: src/cmd/ld/lib.h:349 No newline at end of file
Change-Id: Id21851963f7778364ba9337da3bacd312443f51f
Reviewed-on: https://go-review.googlesource.com/5520
Reviewed-by: Minux Ma <minux@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>
Reconvert using rsc.io/c2go rev 27b3f59.
(Same as last conversion, but C sources have changed
due to merging master into this branch.)
Change-Id: Ib314bb9ac14a726ceb83e2ecf4d1ad2d0b331c38
Reviewed-on: https://go-review.googlesource.com/5471
Reviewed-by: Rob Pike <r@golang.org>
This time for sure.
Change-Id: I77ed6b70d82a6f4ba371afba2f53c8b146ac110f
Reviewed-on: https://go-review.googlesource.com/5530
Reviewed-by: Rob Pike <r@golang.org>
Representation in printout of MRC instruction differs between
32- and 64-bit machines. It's just a hex dump. Fix this one day,
but for now just comment out the instruction.
Change-Id: I4709390659e2e0f2d18ff6f8e762f97cdbfb4c16
Reviewed-on: https://go-review.googlesource.com/5424
Reviewed-by: Rob Pike <r@golang.org>
Add trivial golden test that verifies output matches expectation.
The input is based on the old grammar and is intended to cover
the space of the input language.
PPC64 and ARM only for now; others to follow.
Change-Id: Ib5957822bcafd5b9d4c1dea1c03cc6ee1238f7ef
Reviewed-on: https://go-review.googlesource.com/5421
Reviewed-by: Russ Cox <rsc@golang.org>
As with the previous round for ppc64, this CL fixes a couple of things
that 5a supported but asm did not, both simple.
1) Allow condition code on MRC instruction; this was marked as a TODO.
2) Allow R(n) notation in ARM register shifts. The code needs a rethink
but the tests we're leading toward will make the rewrite easier to test and
trust.
Change-Id: I5b52ad25d177a74cf07e089dddfeeab21863c424
Reviewed-on: https://go-review.googlesource.com/5422
Reviewed-by: Russ Cox <rsc@golang.org>
Applying my post-submit comments from CL 5120.
The rewrite there changed the code from writing to the stack
frame to writing below the stack frame.
Change-Id: Ie7e0563c0c1731fede2bcefeaf3c9d88a0cf4063
Reviewed-on: https://go-review.googlesource.com/5470
Reviewed-by: David Crawshaw <crawshaw@golang.org>
cmd/dist was doing the right thing, but not cmd/go.
Change-Id: I5412140cfc07e806152915cc49db7f63352d01ca
Reviewed-on: https://go-review.googlesource.com/5451
Reviewed-by: Rob Pike <r@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>
