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runtime: convert mcache.flushGen to atomic type

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For #53821

Change-Id: I90ab52a45b7fb6b9e3ff1d6ea97251549306c7aa
Reviewed-on: https://go-review.googlesource.com/c/go/+/425435
Reviewed-by: Michael Pratt <mpratt@google.com>
Reviewed-by: Michael Knyszek <mknyszek@google.com>
Run-TryBot: xie cui <523516579@qq.com>
TryBot-Result: Gopher Robot <gobot@golang.org>
This commit is contained in:
cuiweixie 2022-08-25 11:10:52 +08:00 • committed by Michael Pratt
parent d3b35a4242
commit a25a34abe9
2 changed files with 8 additions and 7 deletions
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13
src/runtime/mcache.go
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@ -50,7 +50,7 @@ type mcache struct {
// was last flushed. If flushGen != mheap_.sweepgen, the spans
// in this mcache are stale and need to the flushed so they
// can be swept. This is done in acquirep.
flushGen uint32
flushGen atomic.Uint32
}
// A gclink is a node in a linked list of blocks, like mlink,
@ -87,7 +87,7 @@ func allocmcache() *mcache {
systemstack(func() {
lock(&mheap_.lock)
c = (*mcache)(mheap_.cachealloc.alloc())
c.flushGen = mheap_.sweepgen
c.flushGen.Store(mheap_.sweepgen)
unlock(&mheap_.lock)
})
for i := range c.alloc {
@ -318,13 +318,14 @@ func (c *mcache) prepareForSweep() {
// allocate-black. However, with this approach it's difficult
// to avoid spilling mark bits into the *next* GC cycle.
sg := mheap_.sweepgen
if c.flushGen == sg {
flushGen := c.flushGen.Load()
if flushGen == sg {
return
} else if c.flushGen != sg-2 {
println("bad flushGen", c.flushGen, "in prepareForSweep; sweepgen", sg)
} else if flushGen != sg-2 {
println("bad flushGen", flushGen, "in prepareForSweep; sweepgen", sg)
throw("bad flushGen")
}
c.releaseAll()
stackcache_clear(c)
atomic.Store(&c.flushGen, mheap_.sweepgen) // Synchronizes with gcStart
c.flushGen.Store(mheap_.sweepgen) // Synchronizes with gcStart
}