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tuklib_cpucores: Use HW_NCPUONLINE on OpenBSD.

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On OpenBSD the number of cores online is often less
than what HW_NCPU would return because OpenBSD disables
simultaneous multi-threading (SMT) by default.

Thanks to Christian Weisgerber.
This commit is contained in:
Lasse Collin 2022-10-20 20:22:50 +03:00
parent 0af861050f
commit 5daa40454b
2 changed files with 14 additions and 0 deletions
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5
m4/tuklib_cpucores.m4
View file

@ -103,7 +103,12 @@ compile error
int
main(void)
{
#ifdef HW_NCPUONLINE
/* This is preferred on OpenBSD, see tuklib_cpucores.c. */
int name[2] = { CTL_HW, HW_NCPUONLINE };
#else
int name[2] = { CTL_HW, HW_NCPU };
#endif
int cpus;
size_t cpus_size = sizeof(cpus);
sysctl(name, 2, &cpus, &cpus_size, NULL, 0);

9
src/common/tuklib_cpucores.c
View file

@ -72,7 +72,16 @@ tuklib_cpucores(void)
}
#elif defined(TUKLIB_CPUCORES_SYSCTL)
// On OpenBSD HW_NCPUONLINE tells the number of processor cores that
// are online so it is preferred over HW_NCPU which also counts cores
// that aren't currently available. The number of cores online is
// often less than HW_NCPU because OpenBSD disables simultaneous
// multi-threading (SMT) by default.
# ifdef HW_NCPUONLINE
int name[2] = { CTL_HW, HW_NCPUONLINE };
# else
int name[2] = { CTL_HW, HW_NCPU };
# endif
int cpus;
size_t cpus_size = sizeof(cpus);
if (sysctl(name, 2, &cpus, &cpus_size, NULL, 0) != -1