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runtime: deduplicate pMask resize code

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Change-Id: I04a9a69904710a488c685cb9eee9c3313ed8e97b
Reviewed-on: https://go-review.googlesource.com/c/go/+/701896
Reviewed-by: Michael Pratt <mpratt@google.com>
Auto-Submit: Michael Knyszek <mknyszek@google.com>
LUCI-TryBot-Result: Go LUCI <golang-scoped@luci-project-accounts.iam.gserviceaccount.com>
This commit is contained in:
Michael Anthony Knyszek 2025-09-03 19:47:28 +00:00 • committed by Gopher Robot
parent fde10c4ce7
commit 69e74b0aac
1 changed files with 20 additions and 17 deletions
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37
src/runtime/proc.go
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@ -5873,8 +5873,6 @@ func procresize(nprocs int32) *p {
}
sched.procresizetime = now
maskWords := (nprocs + 31) / 32
// Grow allp if necessary.
if nprocs > int32(len(allp)) {
// Synchronize with retake, which could be running
@ -5890,19 +5888,8 @@ func procresize(nprocs int32) *p {
allp = nallp
}
if maskWords <= int32(cap(idlepMask)) {
idlepMask = idlepMask[:maskWords]
timerpMask = timerpMask[:maskWords]
} else {
nidlepMask := make([]uint32, maskWords)
// No need to copy beyond len, old Ps are irrelevant.
copy(nidlepMask, idlepMask)
idlepMask = nidlepMask
ntimerpMask := make([]uint32, maskWords)
copy(ntimerpMask, timerpMask)
timerpMask = ntimerpMask
}
idlepMask = idlepMask.resize(nprocs)
timerpMask = timerpMask.resize(nprocs)
unlock(&allpLock)
}
@ -5965,8 +5952,8 @@ func procresize(nprocs int32) *p {
if int32(len(allp)) != nprocs {
lock(&allpLock)
allp = allp[:nprocs]
idlepMask = idlepMask[:maskWords]
timerpMask = timerpMask[:maskWords]
idlepMask = idlepMask.resize(nprocs)
timerpMask = timerpMask.resize(nprocs)
unlock(&allpLock)
}
@ -6905,6 +6892,22 @@ func (p pMask) clear(id int32) {
atomic.And(&p[word], ^mask)
}
// resize resizes the pMask and returns a new one.
//
// The result may alias p, so callers are encouraged to
// discard p. Not safe for concurrent use.
func (p pMask) resize(nprocs int32) pMask {
maskWords := (nprocs + 31) / 32
if maskWords <= int32(cap(p)) {
return p[:maskWords]
}
newMask := make([]uint32, maskWords)
// No need to copy beyond len, old Ps are irrelevant.
copy(newMask, p)
return newMask
}
// pidleput puts p on the _Pidle list. now must be a relatively recent call
// to nanotime or zero. Returns now or the current time if now was zero.
//