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win: compute parallelism from process cpu affinity (#4521)

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Use GetProcessAffinityMask() to estimate the available parallelism.
Before this commit, it simply used the number of available CPUs.

Fixes: https://github.com/libuv/libuv/issues/4520
This commit is contained in:
Ben Noordhuis 2024-08-26 10:22:42 +02:00 committed by GitHub
parent b5eb41d882
commit 58dfb6c89b
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GPG Key ID: B5690EEEBB952194
1 changed files with 11 additions and 7 deletions
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18
src/win/util.c
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@ -512,19 +512,23 @@ int uv_uptime(double* uptime) {
unsigned int uv_available_parallelism(void) { unsigned int uv_available_parallelism(void) {
SYSTEM_INFO info; DWORD_PTR procmask;
unsigned rc; DWORD_PTR sysmask;
int count;
int i;
/* TODO(bnoordhuis) Use GetLogicalProcessorInformationEx() to support systems /* TODO(bnoordhuis) Use GetLogicalProcessorInformationEx() to support systems
* with > 64 CPUs? See https://github.com/libuv/libuv/pull/3458 * with > 64 CPUs? See https://github.com/libuv/libuv/pull/3458
*/ */
GetSystemInfo(&info); count = 0;
if (GetProcessAffinityMask(GetCurrentProcess(), &procmask, &sysmask))
for (i = 0; i < 64; i++) /* a.k.a. count = popcount(procmask); */
count += 1 & (procmask >> i);
rc = info.dwNumberOfProcessors; if (count > 0)
if (rc < 1) return count;
rc = 1;
return rc; return 1;
} }