diff options
| author | Lasse Collin <lasse.collin@tukaani.org> | 2016-10-24 18:51:36 +0300 |
|---|---|---|
| committer | Lasse Collin <lasse.collin@tukaani.org> | 2016-10-24 18:51:36 +0300 |
| commit | df8f446e3ad47e5148b8c8d8b6e519d3ce29cb9d (patch) | |
| tree | af7d6b7d6aa3f05f83375de0ca79142ce8a50b99 /m4 | |
| parent | xz: Fix copying of timestamps on Windows. (diff) | |
| download | xz-df8f446e3ad47e5148b8c8d8b6e519d3ce29cb9d.tar.xz | |
tuklib_cpucores: Add support for sched_getaffinity().
It's available in glibc (GNU/Linux, GNU/kFreeBSD). It's better
than sysconf(_SC_NPROCESSORS_ONLN) because sched_getaffinity()
gives the number of cores available to the process instead of
the total number of cores online.
As a side effect, this commit fixes a bug on GNU/kFreeBSD where
configure would detect the FreeBSD-specific cpuset_getaffinity()
but it wouldn't actually work because on GNU/kFreeBSD it requires
using -lfreebsd-glue when linking. Now the glibc-specific function
will be used instead.
Thanks to Sebastian Andrzej Siewior for the original patch
and testing.
Diffstat (limited to 'm4')
| -rw-r--r-- | m4/tuklib_cpucores.m4 | 30 |
1 files changed, 29 insertions, 1 deletions
diff --git a/m4/tuklib_cpucores.m4 b/m4/tuklib_cpucores.m4 index 468c2db6..a2b09a72 100644 --- a/m4/tuklib_cpucores.m4 +++ b/m4/tuklib_cpucores.m4 @@ -10,6 +10,8 @@ # # Supported methods: # - GetSystemInfo(): Windows (including Cygwin) +# - sched_getaffinity(): glibc (GNU/Linux, GNU/kFreeBSD) +# - cpuset_getaffinity(): FreeBSD # - sysctl(): BSDs, OS/2 # - sysconf(): GNU/Linux, Solaris, Tru64, IRIX, AIX, QNX, Cygwin (but # GetSystemInfo() is used on Cygwin) @@ -45,8 +47,29 @@ compile error #endif ]])], [tuklib_cv_cpucores_method=special], [ +# glibc-based systems (GNU/Linux and GNU/kFreeBSD) have sched_getaffinity(). +# The CPU_COUNT() macro was added in glibc 2.9 so we try to link the +# test program instead of merely compiling it. glibc 2.9 is old enough that +# if someone uses the code on older glibc, the fallback to sysconf() should +# be good enough. +AC_LINK_IFELSE([AC_LANG_SOURCE([[ +#include <sched.h> +int +main(void) +{ + cpu_set_t cpu_mask; + sched_getaffinity(0, sizeof(cpu_mask), &cpu_mask); + return CPU_COUNT(&cpu_mask); +} +]])], [tuklib_cv_cpucores_method=sched_getaffinity], [ + # FreeBSD has both cpuset and sysctl. Look for cpuset first because # it's a better approach. +# +# This test would match on GNU/kFreeBSD too but it would require +# -lfreebsd-glue when linking and thus in the current form this would +# fail on GNU/kFreeBSD. The above test for sched_getaffinity() matches +# on GNU/kFreeBSD so the test below should never run on that OS. AC_COMPILE_IFELSE([AC_LANG_SOURCE([[ #include <sys/param.h> #include <sys/cpuset.h> @@ -120,9 +143,14 @@ main(void) ]])], [tuklib_cv_cpucores_method=pstat_getdynamic], [ tuklib_cv_cpucores_method=unknown -])])])])])]) +])])])])])])]) case $tuklib_cv_cpucores_method in + sched_getaffinity) + AC_DEFINE([TUKLIB_CPUCORES_SCHED_GETAFFINITY], [1], + [Define to 1 if the number of available CPU cores + can be detected with sched_getaffinity()]) + ;; cpuset) AC_DEFINE([TUKLIB_CPUCORES_CPUSET], [1], [Define to 1 if the number of available CPU cores |