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runtime: clean up remaining mark work check

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Now that STW GC marking is unified with concurrent marking, there
should never be mark work remaining in mark termination. Hence, we can
make that check unconditional.

Updates #26903. This is a follow-up to unifying STW GC and concurrent GC.

Change-Id: I43a21df5577635ab379c397a7405ada68d331e03
Reviewed-on: https://go-review.googlesource.com/c/134781
Run-TryBot: Austin Clements <austin@google.com>
TryBot-Result: Gobot Gobot <gobot@golang.org>
Reviewed-by: Rick Hudson <rlh@golang.org>
This commit is contained in:
Austin Clements 2018-08-16 12:17:32 -04:00
parent 1678b2c580
commit 143b13ae82
1 changed files with 5 additions and 21 deletions
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22
src/runtime/mgc.go
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@ -1905,29 +1905,13 @@ func gcMark(start_time int64) {
work.nwait = 0
work.ndone = 0
work.nproc = uint32(gcprocs())
if work.full == 0 && work.nDataRoots+work.nBSSRoots+work.nSpanRoots+work.nStackRoots == 0 {
// There's no work on the work queue and no root jobs
// that can produce work, so don't bother entering the
// getfull() barrier. There will be flushCacheRoots
// work, but that doesn't gray anything.
//
// This should always be the situation after
// concurrent mark.
work.helperDrainBlock = false
} else {
// There's marking work to do. This is the case during
// STW GC. Instruct GC workers
// to block in getfull until all GC workers are in getfull.
//
// TODO(austin): Move STW marking out of
// mark termination and eliminate this code path.
if debug.gcstoptheworld == 0 {
// Check that there's no marking work remaining.
if work.full != 0 || work.nDataRoots+work.nBSSRoots+work.nSpanRoots+work.nStackRoots != 0 {
print("runtime: full=", hex(work.full), " nDataRoots=", work.nDataRoots, " nBSSRoots=", work.nBSSRoots, " nSpanRoots=", work.nSpanRoots, " nStackRoots=", work.nStackRoots, "\n")
panic("non-empty mark queue after concurrent mark")
}
work.helperDrainBlock = true
}
if work.nproc > 1 {
noteclear(&work.alldone)