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| author | Keith Randall <khr@golang.org> | 2021-12-07 09:22:33 -0800 |
|---|---|---|
| committer | Keith Randall <khr@golang.org> | 2022-03-01 18:43:08 +0000 |
| commit | 510ad4561f859f66e5a2d22a73ce8253d19ede3e (patch) | |
| tree | e878180529be323c4928561b32a894ee8254b4c8 /src/runtime/proc.go | |
| parent | d9fd9201ad214e8da769a9338b9d3a5f3e1bc980 (diff) | |
| download | go-510ad4561f859f66e5a2d22a73ce8253d19ede3e.tar.gz go-510ad4561f859f66e5a2d22a73ce8253d19ede3e.zip | |
runtime: improve work stealing randomness
For certain values of GOMAXPROCS, the current code is less random than
it looks. For example with GOMAXPROCS=12, there are 4 coprimes: 1 5 7 11.
That's bad, as 12 and 4 are not relatively prime. So if pos == 2, then we
always pick 7 as the inc. We want to pick pos and inc independently
at random.
Change-Id: I5c7e4f01f9223cbc2db12a685dc0bced2cf39abf
Reviewed-on: https://go-review.googlesource.com/c/go/+/369976
Run-TryBot: Keith Randall <khr@golang.org>
Trust: Keith Randall <khr@golang.org>
TryBot-Result: Gopher Robot <gobot@golang.org>
Reviewed-by: Dmitry Vyukov <dvyukov@google.com>
Diffstat (limited to 'src/runtime/proc.go')
| -rw-r--r-- | src/runtime/proc.go | 2 |
1 files changed, 1 insertions, 1 deletions
diff --git a/src/runtime/proc.go b/src/runtime/proc.go index b997a467ba..df16e0f9b6 100644 --- a/src/runtime/proc.go +++ b/src/runtime/proc.go @@ -6138,7 +6138,7 @@ func (ord *randomOrder) start(i uint32) randomEnum { return randomEnum{ count: ord.count, pos: i % ord.count, - inc: ord.coprimes[i%uint32(len(ord.coprimes))], + inc: ord.coprimes[i/ord.count%uint32(len(ord.coprimes))], } } |