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Ludi Rehak f15761b50b runtime: fix formula for computing number of padding bytes
In order to prevent false sharing of cache lines, structs are
padded with some number of bytes. These bytes are unused, serving
only to make the size of the struct a multiple of the size of the
cache line.

The current calculation of how much to pad is an overestimation,
when the struct size is already a multiple of the cache line size
without padding. For these cases, no padding is necessary, and
the size of the inner pad field should be 0. The bug is that the
pad field is sized to a whole 'nother cache line, wasting space.

Here is the current formula that can never return 0:
cpu.CacheLinePadSize - unsafe.Sizeof(myStruct{})%cpu.CacheLinePadSize

This change simply mods that calculation by cpu.CacheLinePadSize,
so that 0 will be returned instead of cpu.CacheLinePadSize.

Change-Id: I26a2b287171bf47a3b9121873b2722f728381b5e
Reviewed-on: https://go-review.googlesource.com/c/go/+/414214
Reviewed-by: Keith Randall <khr@golang.org>
Run-TryBot: Michael Pratt <mpratt@google.com>
Auto-Submit: Michael Pratt <mpratt@google.com>
Reviewed-by: Keith Randall <khr@google.com>
Reviewed-by: Joedian Reid <joedian@golang.org>
TryBot-Result: Gopher Robot <gobot@golang.org>
2022-08-19 16:04:12 +00:00
.github .github: remove duplicate security link 2022-01-07 17:55:09 +00:00
api crypto/subtle: add XORBytes 2022-08-17 18:47:33 +00:00
doc doc: move Go 1.19 release notes to x/website 2022-08-01 18:07:12 +00:00
lib/time lib/time, time/tzdata: update to 2022b 2022-08-11 20:03:19 +00:00
misc misc/cgo/testcarchive: permit SIGQUIT for TestSignalForwardingExternal 2022-08-19 03:09:05 +00:00
src runtime: fix formula for computing number of padding bytes 2022-08-19 16:04:12 +00:00
test test: add test that caused gccgo crash 2022-08-19 03:32:27 +00:00
.gitattributes
.gitignore internal/buildcfg: move build configuration out of cmd/internal/objabi 2021-04-16 19:20:53 +00:00
CONTRIBUTING.md
LICENSE
PATENTS
README.md README.md: update wiki link 2022-04-26 16:21:18 +00:00
SECURITY.md SECURITY.md: replace golang.org with go.dev 2022-04-26 19:59:47 +00:00
codereview.cfg codereview.cfg: add codereview.cfg for master branch 2021-02-19 18:44:53 +00:00

README.md

The Go Programming Language

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