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| author | Austin Clements <austin@google.com> | 2015-04-22 12:18:01 -0400 |
|---|---|---|
| committer | Austin Clements <austin@google.com> | 2015-04-24 15:12:42 +0000 |
| commit | e5e52f4f2c6f67e41b97fd539c1963f85536c985 (patch) | |
| tree | 02ae2dd6a1c79fdaeb93a21d809ed5f3b842db30 /src | |
| parent | 9406f68e6afd02fd588e8ca05ebb729a4f4b8d0d (diff) | |
| download | go-e5e52f4f2c6f67e41b97fd539c1963f85536c985.tar.xz | |
runtime: factor checking if P run queue is empty
There are a variety of places where we check if a P's run queue is
empty. This test is about to get slightly more complicated, so factor
it out into a new function, runqempty. This function is inlinable, so
this has no effect on performance.
Change-Id: If4a0b01ffbd004937de90d8d686f6ded4aad2c6b
Reviewed-on: https://go-review.googlesource.com/9287
Reviewed-by: Rick Hudson <rlh@golang.org>
Reviewed-by: Russ Cox <rsc@golang.org>
Diffstat (limited to 'src')
| -rw-r--r-- | src/runtime/proc1.go | 16 |
1 files changed, 11 insertions, 5 deletions
diff --git a/src/runtime/proc1.go b/src/runtime/proc1.go index 0359b5571c..d37c4f1a5a 100644 --- a/src/runtime/proc1.go +++ b/src/runtime/proc1.go @@ -1115,7 +1115,7 @@ func startm(_p_ *p, spinning bool) { //go:nowritebarrier func handoffp(_p_ *p) { // if it has local work, start it straight away - if _p_.runqhead != _p_.runqtail || sched.runqsize != 0 { + if !runqempty(_p_) || sched.runqsize != 0 { startm(_p_, false) return } @@ -1369,7 +1369,7 @@ stop: // check all runqueues once again for i := 0; i < int(gomaxprocs); i++ { _p_ := allp[i] - if _p_ != nil && _p_.runqhead != _p_.runqtail { + if _p_ != nil && !runqempty(_p_) { lock(&sched.lock) _p_ = pidleget() unlock(&sched.lock) @@ -2657,7 +2657,7 @@ func procresize(nprocs int32) *p { continue } p.status = _Pidle - if p.runqhead == p.runqtail { + if runqempty(p) { pidleput(p) } else { p.m.set(mget()) @@ -2940,7 +2940,7 @@ func retake(now int64) uint32 { // On the one hand we don't want to retake Ps if there is no other work to do, // but on the other hand we want to retake them eventually // because they can prevent the sysmon thread from deep sleep. - if _p_.runqhead == _p_.runqtail && atomicload(&sched.nmspinning)+atomicload(&sched.npidle) > 0 && pd.syscallwhen+10*1000*1000 > now { + if runqempty(_p_) && atomicload(&sched.nmspinning)+atomicload(&sched.npidle) > 0 && pd.syscallwhen+10*1000*1000 > now { continue } // Need to decrement number of idle locked M's @@ -3220,6 +3220,12 @@ func pidleget() *p { return _p_ } +// runqempty returns true if _p_ has no Gs on its local run queue. +// Note that this test is generally racy. +func runqempty(_p_ *p) bool { + return _p_.runqhead == _p_.runqtail +} + // Try to put g on local runnable queue. // If it's full, put onto global queue. // Executed only by the owner P. @@ -3479,7 +3485,7 @@ func sync_runtime_canSpin(i int) bool { if i >= active_spin || ncpu <= 1 || gomaxprocs <= int32(sched.npidle+sched.nmspinning)+1 { return false } - if p := getg().m.p.ptr(); p.runqhead != p.runqtail { + if p := getg().m.p.ptr(); !runqempty(p) { return false } return true |