mirror of https://github.com/golang/go.git
runtime: faster GC sweep phase
benchmark old ns/op new ns/op delta garbage.BenchmarkParser 3731065750 3715543750 -0.41% garbage.BenchmarkParser-2 3631299750 3495248500 -3.75% garbage.BenchmarkParser-4 3386486000 3339353000 -1.39% garbage.BenchmarkParser-8 3267632000 3286422500 +0.58% garbage.BenchmarkParser-16 3299203000 3316081750 +0.51% garbage.BenchmarkTree 977532888 919453833 -5.94% garbage.BenchmarkTree-2 919948555 853478000 -7.23% garbage.BenchmarkTree-4 841329000 790207000 -6.08% garbage.BenchmarkTree-8 787792777 740380666 -6.01% garbage.BenchmarkTree-16 899257166 846594555 -5.86% garbage.BenchmarkTree2 574876300 571885800 -0.52% garbage.BenchmarkTree2-2 348162700 345888900 -0.65% garbage.BenchmarkTree2-4 184912500 179137000 -3.22% garbage.BenchmarkTree2-8 104243900 103485600 -0.73% garbage.BenchmarkTree2-16 97269500 85137100 -14.25% garbage.BenchmarkParserPause 141101976 157746974 +11.80% garbage.BenchmarkParserPause-2 103096051 83043048 -19.45% garbage.BenchmarkParserPause-4 52153133 45951111 -11.89% garbage.BenchmarkParserPause-8 36730190 38901024 +5.91% garbage.BenchmarkParserPause-16 32678875 29578585 -9.49% garbage.BenchmarkTreePause 29487065 29648439 +0.55% garbage.BenchmarkTreePause-2 22443494 21306159 -5.07% garbage.BenchmarkTreePause-4 15799691 14985647 -5.15% garbage.BenchmarkTreePause-8 10768112 9531420 -12.97% garbage.BenchmarkTreePause-16 16329891 15205158 -6.89% garbage.BenchmarkTree2Pause 2586957240 2577533200 -0.36% garbage.BenchmarkTree2Pause-2 1683383760 1673923800 -0.56% garbage.BenchmarkTree2Pause-4 1102860320 1074040280 -2.68% garbage.BenchmarkTree2Pause-8 902627920 886122400 -1.86% garbage.BenchmarkTree2Pause-16 856470920 804152320 -6.50% garbage.BenchmarkParserLastPause 277316000 280839000 +1.25% garbage.BenchmarkParserLastPause-2 179446000 163687000 -8.78% garbage.BenchmarkParserLastPause-4 106752000 94144000 -11.81% garbage.BenchmarkParserLastPause-8 57758000 61640000 +6.72% garbage.BenchmarkParserLastPause-16 51235000 42552000 -16.95% garbage.BenchmarkTreeLastPause 45244000 50786000 +12.25% garbage.BenchmarkTreeLastPause-2 37163000 34654000 -6.75% garbage.BenchmarkTreeLastPause-4 24178000 21967000 -9.14% garbage.BenchmarkTreeLastPause-8 20390000 15648000 -30.30% garbage.BenchmarkTreeLastPause-16 22398000 20180000 -9.90% garbage.BenchmarkTree2LastPause 5748706000 5718809000 -0.52% garbage.BenchmarkTree2LastPause-2 3481570000 3458844000 -0.65% garbage.BenchmarkTree2LastPause-4 1849073000 1791330000 -3.22% garbage.BenchmarkTree2LastPause-8 1042375000 1034811000 -0.73% garbage.BenchmarkTree2LastPause-16 972637000 851323000 -14.25% There is also visible improvement in consumed CPU time: tree2 -heapsize=8000000000 -cpus=12 before: 248.74user 6.36system 0:52.74elapsed 483%CPU after: 229.86user 6.33system 0:51.08elapsed 462%CPU -1.66s of real time, but -18.91s of consumed CPU time R=golang-dev CC=golang-dev https://golang.org/cl/6215065
This commit is contained in:
Dmitriy Vyukov
Russ Cox
parent
581e7c2a78
commit
845aa1fc2c
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@ -120,10 +120,9 @@ static struct {
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uint32 nproc;
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volatile uint32 nwait;
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volatile uint32 ndone;
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volatile uint32 debugmarkdone;
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Note alldone;
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Lock markgate;
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Lock sweepgate;
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uint32 spanidx;
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ParFor *sweepfor;
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Lock;
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byte *chunk;
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@ -720,40 +719,10 @@ handlespecial(byte *p, uintptr size)
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return true;
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}
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static void sweepspan(MSpan *s);
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// Sweep frees or collects finalizers for blocks not marked in the mark phase.
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// It clears the mark bits in preparation for the next GC round.
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static void
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sweep(void)
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{
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MSpan *s, **allspans;
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int64 now;
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uint32 spanidx, nspan;
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now = runtime·nanotime();
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nspan = runtime·mheap.nspan;
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allspans = runtime·mheap.allspans;
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for(;;) {
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spanidx = runtime·xadd(&work.spanidx, 1) - 1;
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if(spanidx >= nspan)
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break;
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s = allspans[spanidx];
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// Stamp newly unused spans. The scavenger will use that
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// info to potentially give back some pages to the OS.
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if(s->state == MSpanFree && s->unusedsince == 0)
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s->unusedsince = now;
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if(s->state != MSpanInUse)
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continue;
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sweepspan(s);
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}
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}
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static void
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sweepspan(MSpan *s)
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sweepspan(ParFor *desc, uint32 idx)
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{
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int32 cl, n, npages;
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uintptr size;
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@ -762,7 +731,16 @@ sweepspan(MSpan *s)
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byte *arena_start;
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MLink *start, *end;
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int32 nfree;
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MSpan *s;
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USED(&desc);
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s = runtime·mheap.allspans[idx];
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// Stamp newly unused spans. The scavenger will use that
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// info to potentially give back some pages to the OS.
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if(s->state == MSpanFree && s->unusedsince == 0)
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s->unusedsince = runtime·nanotime();
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if(s->state != MSpanInUse)
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return;
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arena_start = runtime·mheap.arena_start;
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p = (byte*)(s->start << PageShift);
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cl = s->sizeclass;
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@ -847,16 +825,15 @@ sweepspan(MSpan *s)
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void
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runtime·gchelper(void)
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{
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// Wait until main proc is ready for mark help.
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runtime·lock(&work.markgate);
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runtime·unlock(&work.markgate);
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scanblock(nil, 0);
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// Wait until main proc is ready for sweep help.
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runtime·lock(&work.sweepgate);
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runtime·unlock(&work.sweepgate);
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sweep();
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if(DebugMark) {
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// wait while the main thread executes mark(debug_scanblock)
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while(runtime·atomicload(&work.debugmarkdone) == 0)
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runtime·usleep(10);
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}
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runtime·parfordo(work.sweepfor);
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if(runtime·xadd(&work.ndone, +1) == work.nproc-1)
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runtime·notewakeup(&work.alldone);
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}
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@ -972,33 +949,38 @@ runtime·gc(int32 force)
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obj0 = mstats.nmalloc - mstats.nfree;
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}
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runtime·lock(&work.markgate);
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runtime·lock(&work.sweepgate);
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work.nwait = 0;
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work.ndone = 0;
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work.debugmarkdone = 0;
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work.nproc = runtime·gcprocs();
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if(work.sweepfor == nil)
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work.sweepfor = runtime·parforalloc(MaxGcproc);
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runtime·parforsetup(work.sweepfor, work.nproc, runtime·mheap.nspan, nil, true, sweepspan);
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if(work.nproc > 1) {
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runtime·noteclear(&work.alldone);
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runtime·helpgc(work.nproc);
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}
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work.nwait = 0;
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work.ndone = 0;
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runtime·unlock(&work.markgate); // let the helpers in
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mark(scanblock);
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if(DebugMark)
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if(DebugMark) {
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mark(debug_scanblock);
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runtime·atomicstore(&work.debugmarkdone, 1);
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}
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t1 = runtime·nanotime();
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work.spanidx = 0;
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runtime·unlock(&work.sweepgate); // let the helpers in
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sweep();
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if(work.nproc > 1)
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runtime·notesleep(&work.alldone);
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runtime·parfordo(work.sweepfor);
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t2 = runtime·nanotime();
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stealcache();
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cachestats(&stats);
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if(work.nproc > 1)
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runtime·notesleep(&work.alldone);
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stats.nprocyield += work.sweepfor->nprocyield;
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stats.nosyield += work.sweepfor->nosyield;
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stats.nsleep += work.sweepfor->nsleep;
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mstats.next_gc = mstats.heap_alloc+mstats.heap_alloc*gcpercent/100;
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m->gcing = 0;
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@ -1027,20 +1009,21 @@ runtime·gc(int32 force)
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if(gctrace) {
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runtime·printf("gc%d(%d): %D+%D+%D ms, %D -> %D MB %D -> %D (%D-%D) objects,"
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" %D(%D) handoff, %D/%D/%D yields\n",
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" %D(%D) handoff, %D(%D) steal, %D/%D/%D yields\n",
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mstats.numgc, work.nproc, (t1-t0)/1000000, (t2-t1)/1000000, (t3-t2)/1000000,
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heap0>>20, heap1>>20, obj0, obj1,
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mstats.nmalloc, mstats.nfree,
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stats.nhandoff, stats.nhandoffcnt,
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work.sweepfor->nsteal, work.sweepfor->nstealcnt,
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stats.nprocyield, stats.nosyield, stats.nsleep);
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}
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runtime·MProf_GC();
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runtime·semrelease(&runtime·worldsema);
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runtime·starttheworld();
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// give the queued finalizers, if any, a chance to run
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if(finq != nil)
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// give the queued finalizers, if any, a chance to run
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if(finq != nil)
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runtime·gosched();
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if(gctrace > 1 && !force)
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