aboutsummaryrefslogtreecommitdiff
path: root/m4
diff options
context:
space:
mode:
authorLasse Collin <lasse.collin@tukaani.org>2016-10-24 18:51:36 +0300
committerLasse Collin <lasse.collin@tukaani.org>2016-10-24 18:51:36 +0300
commitdf8f446e3ad47e5148b8c8d8b6e519d3ce29cb9d (patch)
treeaf7d6b7d6aa3f05f83375de0ca79142ce8a50b99 /m4
parentxz: Fix copying of timestamps on Windows. (diff)
downloadxz-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.m430
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