From dcd9e5bc0f5899c4be5d06147c4cdbbda5b49b01 Mon Sep 17 00:00:00 2001 From: Austin Clements Date: Mon, 26 Oct 2015 17:07:02 -0400 Subject: [PATCH] runtime: make putfull start mark workers MIME-Version: 1.0 Content-Type: text/plain; charset=utf8 Content-Transfer-Encoding: 8bit Currently we depend on the good graces and timing of the scheduler to get opportunities to start dedicated mark workers. In the worst case, it may take 10ms to get dedicated mark workers going at the beginning of mark 1 and mark 2 or after the amount of available work has dropped and gone back up. Instead of waiting for the regular preemption logic to get around to us, make putfull enlist a random P if we're not already running enough dedicated workers. This should improve performance stability of the garbage collector and is likely to improve the overall performance somewhat. No overall effect on the go1 benchmarks. It speeds up the garbage benchmark by 12%, which more than counters the performance loss from the previous commit. name old time/op new time/op delta XBenchGarbage-12 6.32ms ± 4% 5.58ms ± 2% -11.68% (p=0.000 n=20+16) name old time/op new time/op delta BinaryTree17-12 3.18s ± 5% 3.12s ± 4% -1.83% (p=0.021 n=20+20) Fannkuch11-12 2.50s ± 2% 2.46s ± 2% -1.57% (p=0.000 n=18+19) FmtFprintfEmpty-12 50.8ns ± 3% 50.4ns ± 3% ~ (p=0.184 n=20+20) FmtFprintfString-12 167ns ± 2% 171ns ± 1% +2.46% (p=0.000 n=20+19) FmtFprintfInt-12 161ns ± 2% 163ns ± 2% +1.81% (p=0.000 n=20+20) FmtFprintfIntInt-12 269ns ± 1% 266ns ± 1% -0.81% (p=0.002 n=19+20) FmtFprintfPrefixedInt-12 237ns ± 2% 231ns ± 2% -2.86% (p=0.000 n=20+20) FmtFprintfFloat-12 313ns ± 2% 313ns ± 1% ~ (p=0.681 n=20+20) FmtManyArgs-12 1.05µs ± 2% 1.03µs ± 1% -2.26% (p=0.000 n=20+20) GobDecode-12 8.66ms ± 1% 8.67ms ± 1% ~ (p=0.380 n=19+20) GobEncode-12 6.56ms ± 1% 6.56ms ± 2% ~ (p=0.607 n=19+20) Gzip-12 317ms ± 1% 314ms ± 2% -1.10% (p=0.000 n=20+19) Gunzip-12 42.1ms ± 1% 42.2ms ± 1% +0.27% (p=0.044 n=20+19) HTTPClientServer-12 62.7µs ± 1% 62.0µs ± 1% -1.04% (p=0.000 n=19+18) JSONEncode-12 16.7ms ± 1% 16.8ms ± 2% +0.59% (p=0.021 n=20+20) JSONDecode-12 58.2ms ± 1% 61.4ms ± 2% +5.43% (p=0.000 n=18+19) Mandelbrot200-12 3.84ms ± 1% 3.87ms ± 2% +0.79% (p=0.008 n=18+20) GoParse-12 3.86ms ± 2% 3.76ms ± 2% -2.60% (p=0.000 n=20+20) RegexpMatchEasy0_32-12 100ns ± 2% 100ns ± 1% -0.68% (p=0.005 n=18+15) RegexpMatchEasy0_1K-12 332ns ± 1% 342ns ± 1% +3.16% (p=0.000 n=19+19) RegexpMatchEasy1_32-12 82.9ns ± 3% 83.0ns ± 2% ~ (p=0.906 n=19+20) RegexpMatchEasy1_1K-12 487ns ± 1% 494ns ± 1% +1.50% (p=0.000 n=17+20) RegexpMatchMedium_32-12 131ns ± 2% 130ns ± 1% ~ (p=0.686 n=19+20) RegexpMatchMedium_1K-12 39.6µs ± 1% 39.2µs ± 1% -1.09% (p=0.000 n=18+19) RegexpMatchHard_32-12 2.04µs ± 1% 2.04µs ± 2% ~ (p=0.804 n=20+20) RegexpMatchHard_1K-12 61.7µs ± 2% 61.3µs ± 2% ~ (p=0.052 n=18+20) Revcomp-12 529ms ± 2% 533ms ± 1% +0.83% (p=0.003 n=20+19) Template-12 70.7ms ± 2% 71.0ms ± 2% ~ (p=0.065 n=20+19) TimeParse-12 351ns ± 2% 355ns ± 1% +1.25% (p=0.000 n=19+20) TimeFormat-12 362ns ± 2% 373ns ± 1% +2.83% (p=0.000 n=18+20) [Geo mean] 62.2µs 62.3µs +0.13% name old speed new speed delta GobDecode-12 88.6MB/s ± 1% 88.5MB/s ± 1% ~ (p=0.392 n=19+20) GobEncode-12 117MB/s ± 1% 117MB/s ± 1% ~ (p=0.622 n=19+20) Gzip-12 61.1MB/s ± 1% 61.8MB/s ± 2% +1.11% (p=0.000 n=20+19) Gunzip-12 461MB/s ± 1% 460MB/s ± 1% -0.27% (p=0.044 n=20+19) JSONEncode-12 116MB/s ± 1% 115MB/s ± 2% -0.58% (p=0.022 n=20+20) JSONDecode-12 33.3MB/s ± 1% 31.6MB/s ± 2% -5.15% (p=0.000 n=18+19) GoParse-12 15.0MB/s ± 2% 15.4MB/s ± 2% +2.66% (p=0.000 n=20+20) RegexpMatchEasy0_32-12 317MB/s ± 2% 319MB/s ± 2% ~ (p=0.052 n=20+20) RegexpMatchEasy0_1K-12 3.08GB/s ± 1% 2.99GB/s ± 1% -3.07% (p=0.000 n=19+19) RegexpMatchEasy1_32-12 386MB/s ± 3% 386MB/s ± 2% ~ (p=0.939 n=19+20) RegexpMatchEasy1_1K-12 2.10GB/s ± 1% 2.07GB/s ± 1% -1.46% (p=0.000 n=17+20) RegexpMatchMedium_32-12 7.62MB/s ± 2% 7.64MB/s ± 1% ~ (p=0.702 n=19+20) RegexpMatchMedium_1K-12 25.9MB/s ± 1% 26.1MB/s ± 2% +0.99% (p=0.000 n=18+20) RegexpMatchHard_32-12 15.7MB/s ± 1% 15.7MB/s ± 2% ~ (p=0.723 n=20+20) RegexpMatchHard_1K-12 16.6MB/s ± 2% 16.7MB/s ± 2% ~ (p=0.052 n=18+20) Revcomp-12 481MB/s ± 2% 477MB/s ± 1% -0.83% (p=0.003 n=20+19) Template-12 27.5MB/s ± 2% 27.3MB/s ± 2% ~ (p=0.062 n=20+19) [Geo mean] 99.4MB/s 99.1MB/s -0.35% Change-Id: I914d8cadded5a230509d118164a4c201601afc06 Reviewed-on: https://go-review.googlesource.com/16298 Reviewed-by: Rick Hudson --- src/runtime/mgc.go | 33 +++++++++++++++++++++++++++++++++ src/runtime/mgcwork.go | 6 ++++++ 2 files changed, 39 insertions(+) diff --git a/src/runtime/mgc.go b/src/runtime/mgc.go index 1ab42a8105..88cee5b8f6 100644 --- a/src/runtime/mgc.go +++ b/src/runtime/mgc.go @@ -574,6 +574,39 @@ func (c *gcControllerState) endCycle() { } } +// enlistWorker encourages another dedicated mark worker to start on +// another P if there are spare worker slots. It is used by putfull +// when more work is made available. +// +//go:nowritebarrier +func (c *gcControllerState) enlistWorker() { + if c.dedicatedMarkWorkersNeeded <= 0 { + return + } + // Pick a random other P to preempt. + if gomaxprocs <= 1 { + return + } + gp := getg() + if gp == nil || gp.m == nil || gp.m.p == 0 { + return + } + myID := gp.m.p.ptr().id + for tries := 0; tries < 5; tries++ { + id := int32(fastrand1() % uint32(gomaxprocs-1)) + if id >= myID { + id++ + } + p := allp[id] + if p.status != _Prunning { + continue + } + if preemptone(p) { + return + } + } +} + // findRunnableGCWorker returns the background mark worker for _p_ if it // should be run. This must only be called when gcBlackenEnabled != 0. func (c *gcControllerState) findRunnableGCWorker(_p_ *p) *g { diff --git a/src/runtime/mgcwork.go b/src/runtime/mgcwork.go index 43d5db2fab..1d66200bec 100644 --- a/src/runtime/mgcwork.go +++ b/src/runtime/mgcwork.go @@ -363,6 +363,12 @@ func putfull(b *workbuf, entry int) { b.checknonempty() b.logput(entry) lfstackpush(&work.full, &b.node) + + // We just made more work available. Let the GC controller + // know so it can encourage more workers to run. + if gcphase == _GCmark { + gcController.enlistWorker() + } } // trygetfull tries to get a full or partially empty workbuffer. -- 2.48.1