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runtime: allocate goroutine ids in batches

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Helps reduce contention on sched.goidgen.

benchmark                               old ns/op    new ns/op    delta
BenchmarkCreateGoroutines-16                  259          237   -8.49%
BenchmarkCreateGoroutinesParallel-16          127           43  -66.06%

R=golang-codereviews, dave, bradfitz, khr
CC=golang-codereviews, rsc
https://golang.org/cl/46970043
This commit is contained in:
Dmitriy Vyukov 2014-01-22 10:34:36 +04:00
parent 8a3c587dc1
commit 98b50b89a8
2 changed files with 23 additions and 6 deletions
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21
src/pkg/runtime/proc.c
View File

@ -58,9 +58,16 @@ struct Sched {
int32 profilehz; // cpu profiling rate
};
enum
{
// The max value of GOMAXPROCS.
// There are no fundamental restrictions on the value.
enum { MaxGomaxprocs = 1<<8 };
MaxGomaxprocs = 1<<8,
// Number of goroutine ids to grab from runtime·sched.goidgen to local per-P cache at once.
// 16 seems to provide enough amortization, but other than that it's mostly arbitrary number.
GoidCacheBatch = 16,
};
Sched runtime·sched;
int32 runtime·gomaxprocs;
@ -1752,6 +1759,7 @@ runtime·newproc1(FuncVal *fn, byte *argp, int32 narg, int32 nret, void *callerp
{
byte *sp;
G *newg;
P *p;
int32 siz;
//runtime·printf("newproc1 %p %p narg=%d nret=%d\n", fn->fn, argp, narg, nret);
@ -1766,7 +1774,8 @@ runtime·newproc1(FuncVal *fn, byte *argp, int32 narg, int32 nret, void *callerp
if(siz > StackMin - 1024)
runtime·throw("runtime.newproc: function arguments too large for new goroutine");
if((newg = gfget(m->p)) != nil) {
p = m->p;
if((newg = gfget(p)) != nil) {
if(newg->stackguard - StackGuard != newg->stack0)
runtime·throw("invalid stack in newg");
} else {
@ -1790,11 +1799,15 @@ runtime·newproc1(FuncVal *fn, byte *argp, int32 narg, int32 nret, void *callerp
runtime·gostartcallfn(&newg->sched, fn);
newg->gopc = (uintptr)callerpc;
newg->status = Grunnable;
newg->goid = runtime·xadd64(&runtime·sched.goidgen, 1);
if(p->goidcache == p->goidcacheend) {
p->goidcache = runtime·xadd64(&runtime·sched.goidgen, GoidCacheBatch);
p->goidcacheend = p->goidcache + GoidCacheBatch;
}
newg->goid = p->goidcache++;
newg->panicwrap = 0;
if(raceenabled)
newg->racectx = runtime·racegostart((void*)callerpc);
runqput(m->p, newg);
runqput(p, newg);
if(runtime·atomicload(&runtime·sched.npidle) != 0 && runtime·atomicload(&runtime·sched.nmspinning) == 0 && fn->fn != runtime·main) // TODO: fast atomic
wakep();

4
src/pkg/runtime/runtime.h
View File

@ -385,6 +385,10 @@ struct P
MCache* mcache;
Defer* deferpool[5]; // pool of available Defer structs of different sizes (see panic.c)
// Cache of goroutine ids, amortizes accesses to runtime·sched.goidgen.
uint64 goidcache;
uint64 goidcacheend;
// Queue of runnable goroutines.
uint32 runqhead;
uint32 runqtail;