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| author | David Chase <drchase@google.com> | 2020-11-17 19:54:31 -0500 |
|---|---|---|
| committer | David Chase <drchase@google.com> | 2021-04-30 19:41:02 +0000 |
| commit | 0bbfc5c31eb4cb77f12e10c73d5462377e66b06c (patch) | |
| tree | 7641ae1ee24c4e0c425ef8e023844506398de440 /src/runtime/mcache.go | |
| parent | 41afd3af42bd8028a1740c30a2b745105b4063d2 (diff) | |
| download | go-0bbfc5c31eb4cb77f12e10c73d5462377e66b06c.tar.gz go-0bbfc5c31eb4cb77f12e10c73d5462377e66b06c.zip | |
runtime: break up large calls to memclrNoHeapPointers to allow preemption
If something "huge" is allocated, and the zeroing is trivial (no pointers
involved) then zero it by chunks in a loop so that preemption can occur,
not all in a single non-preemptible call.
Benchmarking suggests that 256K is the best chunk size.
Updates #42642.
Change-Id: I94015e467eaa098c59870e479d6d83bc88efbfb4
Reviewed-on: https://go-review.googlesource.com/c/go/+/270943
Trust: David Chase <drchase@google.com>
Run-TryBot: David Chase <drchase@google.com>
TryBot-Result: Go Bot <gobot@golang.org>
Reviewed-by: Michael Knyszek <mknyszek@google.com>
Diffstat (limited to 'src/runtime/mcache.go')
| -rw-r--r-- | src/runtime/mcache.go | 9 |
1 files changed, 6 insertions, 3 deletions
diff --git a/src/runtime/mcache.go b/src/runtime/mcache.go index 097e4a5ade..a9e959109a 100644 --- a/src/runtime/mcache.go +++ b/src/runtime/mcache.go @@ -206,7 +206,10 @@ func (c *mcache) refill(spc spanClass) { } // allocLarge allocates a span for a large object. -func (c *mcache) allocLarge(size uintptr, needzero bool, noscan bool) *mspan { +// The boolean result indicates whether the span is known-zeroed. +// If it did not need to be zeroed, it may not have been zeroed; +// but if it came directly from the OS, it is already zeroed. +func (c *mcache) allocLarge(size uintptr, needzero bool, noscan bool) (*mspan, bool) { if size+_PageSize < size { throw("out of memory") } @@ -221,7 +224,7 @@ func (c *mcache) allocLarge(size uintptr, needzero bool, noscan bool) *mspan { deductSweepCredit(npages*_PageSize, npages) spc := makeSpanClass(0, noscan) - s := mheap_.alloc(npages, spc, needzero) + s, isZeroed := mheap_.alloc(npages, spc, needzero) if s == nil { throw("out of memory") } @@ -245,7 +248,7 @@ func (c *mcache) allocLarge(size uintptr, needzero bool, noscan bool) *mspan { mheap_.central[spc].mcentral.fullSwept(mheap_.sweepgen).push(s) s.limit = s.base() + size heapBitsForAddr(s.base()).initSpan(s) - return s + return s, isZeroed } func (c *mcache) releaseAll() { |