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runtime: simplify nobarrierWakeTime

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Also use the simplified nobarrierWakeTime in findrunnable, as it no
longer needs the current time.

Change-Id: I77b125d6a184dde0aeb517fc068164c274f0a046
Reviewed-on: https://go-review.googlesource.com/c/go/+/266304
Trust: Ian Lance Taylor <iant@golang.org>
Run-TryBot: Ian Lance Taylor <iant@golang.org>
TryBot-Result: Go Bot <gobot@golang.org>
Reviewed-by: Michael Knyszek <mknyszek@google.com>
Reviewed-by: Michael Pratt <mpratt@google.com>
This commit is contained in:
Ian Lance Taylor 2020-10-29 16:23:27 -07:00
parent a313eec386
commit e02ab89eb8
2 changed files with 9 additions and 19 deletions
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15
src/runtime/proc.go
View File

@ -2659,18 +2659,9 @@ stop:
// checkTimers here because it calls adjusttimers which may need to allocate // checkTimers here because it calls adjusttimers which may need to allocate
// memory, and that isn't allowed when we don't have an active P. // memory, and that isn't allowed when we don't have an active P.
for _, _p_ := range allpSnapshot { for _, _p_ := range allpSnapshot {
// This is similar to nobarrierWakeTime, but minimizes calls to w := nobarrierWakeTime(_p_)
// nanotime. if w != 0 && (pollUntil == 0 || w < pollUntil) {
if atomic.Load(&_p_.adjustTimers) > 0 { pollUntil = w
if now == 0 {
now = nanotime()
}
pollUntil = now
} else {
w := int64(atomic.Load64(&_p_.timer0When))
if w != 0 && (pollUntil == 0 || w < pollUntil) {
pollUntil = w
}
} }
} }
if pollUntil != 0 { if pollUntil != 0 {

13
src/runtime/time.go
View File

@ -742,16 +742,15 @@ func addAdjustedTimers(pp *p, moved []*timer) {
// nobarrierWakeTime looks at P's timers and returns the time when we // nobarrierWakeTime looks at P's timers and returns the time when we
// should wake up the netpoller. It returns 0 if there are no timers. // should wake up the netpoller. It returns 0 if there are no timers.
// This function is invoked when dropping a P, and must run without // This function is invoked when dropping a P, and must run without
// any write barriers. Therefore, if there are any timers that needs // any write barriers.
// to be moved earlier, it conservatively returns the current time.
// The netpoller M will wake up and adjust timers before sleeping again.
//go:nowritebarrierrec //go:nowritebarrierrec
func nobarrierWakeTime(pp *p) int64 { func nobarrierWakeTime(pp *p) int64 {
if atomic.Load(&pp.adjustTimers) > 0 { next := int64(atomic.Load64(&pp.timer0When))
return nanotime() nextAdj := int64(atomic.Load64(&pp.timerModifiedEarliest))
} else { if next == 0 || (nextAdj != 0 && nextAdj < next) {
return int64(atomic.Load64(&pp.timer0When)) next = nextAdj
} }
return next
} }
// runtimer examines the first timer in timers. If it is ready based on now, // runtimer examines the first timer in timers. If it is ready based on now,