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| author | Michael Anthony Knyszek <mknyszek@google.com> | 2024-09-18 01:58:50 +0000 |
|---|---|---|
| committer | Gopher Robot <gobot@golang.org> | 2024-10-21 14:47:04 +0000 |
| commit | 56fb8350c835d1ccf0e6cdb8f753c85e2e0748a8 (patch) | |
| tree | f2024aa2b47f37cda439a53d6869056c87c1edff /src/runtime/malloc.go | |
| parent | d94b7a187685942579e7d7dc00bf58448cdafce8 (diff) | |
| download | go-56fb8350c835d1ccf0e6cdb8f753c85e2e0748a8.tar.xz | |
runtime: don't call span.heapBits in writeHeapBitsSmall
For whatever reason, span.heapBits is kind of slow. It accounts for
about a quarter of the cost of writeHeapBitsSmall, which is absurd. We
get a nice speed improvement for small allocations by eliminating this
call.
│ before │ after │
│ sec/op │ sec/op vs base │
MallocTypeInfo16-4 29.47n ± 1% 27.02n ± 1% -8.31% (p=0.002 n=6)
Change-Id: I6270e26902e5a9254cf1503fac81c3c799c59d6a
Reviewed-on: https://go-review.googlesource.com/c/go/+/614255
Reviewed-by: Keith Randall <khr@golang.org>
LUCI-TryBot-Result: Go LUCI <golang-scoped@luci-project-accounts.iam.gserviceaccount.com>
Reviewed-by: Keith Randall <khr@google.com>
Auto-Submit: Michael Knyszek <mknyszek@google.com>
Diffstat (limited to 'src/runtime/malloc.go')
| -rw-r--r-- | src/runtime/malloc.go | 10 |
1 files changed, 10 insertions, 0 deletions
diff --git a/src/runtime/malloc.go b/src/runtime/malloc.go index 7076ced453..71dda120d4 100644 --- a/src/runtime/malloc.go +++ b/src/runtime/malloc.go @@ -427,8 +427,15 @@ func mallocinit() { // Check that the minimum size (exclusive) for a malloc header is also // a size class boundary. This is important to making sure checks align // across different parts of the runtime. + // + // While we're here, also check to make sure all these size classes' + // span sizes are one page. Some code relies on this. minSizeForMallocHeaderIsSizeClass := false + sizeClassesUpToMinSizeForMallocHeaderAreOnePage := true for i := 0; i < len(class_to_size); i++ { + if class_to_allocnpages[i] > 1 { + sizeClassesUpToMinSizeForMallocHeaderAreOnePage = false + } if minSizeForMallocHeader == uintptr(class_to_size[i]) { minSizeForMallocHeaderIsSizeClass = true break @@ -437,6 +444,9 @@ func mallocinit() { if !minSizeForMallocHeaderIsSizeClass { throw("min size of malloc header is not a size class boundary") } + if !sizeClassesUpToMinSizeForMallocHeaderAreOnePage { + throw("expected all size classes up to min size for malloc header to fit in one-page spans") + } // Check that the pointer bitmap for all small sizes without a malloc header // fits in a word. if minSizeForMallocHeader/goarch.PtrSize > 8*goarch.PtrSize { |