thread-utils.c: detect CPU count on older BSD-like systems

Not all systems support using sysconf to detect the number
of available CPU cores.  Older BSD and BSD-derived systems
only provide the information via the sysctl function.

If HAVE_BSD_SYSCTL is defined attempt to retrieve the number
of available CPU cores using the sysctl function.

If HAVE_BSD_SYSCTL is not defined or the sysctl function
fails, we still attempt to get the information via sysconf.

Signed-off-by: Kyle J. McKay <mackyle@gmail.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>

diff --git a/thread-utils.c b/thread-utils.c
index 97396a75ae4fc3f118750dd687fba85e3fc526cc..a2135e0743ac60d8d4512210a81bac2102948fa1 100644 (file)
--- a/thread-utils.c
+++ b/thread-utils.c
@@ -35,7 +35,23 @@ int online_cpus(void)
 
        if (!pstat_getdynamic(&psd, sizeof(psd), (size_t)1, 0))
                return (int)psd.psd_proc_cnt;
-#endif
+#elif defined(HAVE_BSD_SYSCTL) && defined(HW_NCPU)
+       int mib[2];
+       size_t len;
+       int cpucount;
+
+       mib[0] = CTL_HW;
+#  ifdef HW_AVAILCPU
+       mib[1] = HW_AVAILCPU;
+       len = sizeof(cpucount);
+       if (!sysctl(mib, 2, &cpucount, &len, NULL, 0))
+               return cpucount;
+#  endif /* HW_AVAILCPU */
+       mib[1] = HW_NCPU;
+       len = sizeof(cpucount);
+       if (!sysctl(mib, 2, &cpucount, &len, NULL, 0))
+               return cpucount;
+#endif /* defined(HAVE_BSD_SYSCTL) && defined(HW_NCPU) */
 
 #ifdef _SC_NPROCESSORS_ONLN
        if ((ncpus = (long)sysconf(_SC_NPROCESSORS_ONLN)) > 0)