runtime: eliminate the redundant for loop in runqget()

Change-Id: If9b283bbef3ff12a64d34b07491aee3396852f05
Reviewed-on: https://go-review.googlesource.com/c/go/+/317509
Reviewed-by: Austin Clements <austin@google.com>
Run-TryBot: Austin Clements <austin@google.com>
TryBot-Result: Go Bot <gobot@golang.org>
Trust: Keith Randall <khr@golang.org>
This commit is contained in:
Andy Pan 2021-05-06 09:04:03 +08:00 committed by Austin Clements
parent f118d145a5
commit 3920d6f208

View file

@ -5994,14 +5994,12 @@ func runqputbatch(pp *p, q *gQueue, qsize int) {
// Executed only by the owner P.
func runqget(_p_ *p) (gp *g, inheritTime bool) {
// If there's a runnext, it's the next G to run.
for {
next := _p_.runnext
if next == 0 {
break
}
if _p_.runnext.cas(next, 0) {
return next.ptr(), true
}
next := _p_.runnext
// If the runnext is non-0 and the CAS fails, it could only have been stolen by another P,
// because other Ps can race to set runnext to 0, but only the current P can set it to non-0.
// Hence, there's no need to retry this CAS if it falls.
if next != 0 && _p_.runnext.cas(next, 0) {
return next.ptr(), true
}
for {