Only use available CPUs

Not all CPUs may be available for the current process. Some CPUs
may be offline, others may not be included in the process affinity
mask. In such cases too many threads will be created, which will
then compete unnecessarily for CPU time.

Use sched_getaffinity() to determine the correct number of threads
to create.

1 files changed, 9 insertions, 5 deletions

diff --git a/lib/common/writer/init.c b/lib/common/writer/init.c
index 06726ce..7940c3f 100644
--- a/lib/common/writer/init.c
+++ b/lib/common/writer/init.c
@@ -10,16 +10,20 @@
 
 #include <string.h>
 #include <stdlib.h>
+#include <unistd.h>
 
-#ifdef HAVE_SYS_SYSINFO_H
-#include <sys/sysinfo.h>
+#ifdef HAVE_SCHED_GETAFFINITY
+#include <sched.h>
 
 static size_t os_get_num_jobs(void)
 {
-	int nprocs;
+	cpu_set_t cpu_set;
+	CPU_ZERO(&cpu_set);
 
-	nprocs = get_nprocs_conf();
-	return nprocs < 1 ? 1 : nprocs;
+	if (sched_getaffinity(0, sizeof cpu_set, &cpu_set) == -1)
+		return 1;
+	else
+		return CPU_COUNT(&cpu_set);
 }
 #else
 static size_t os_get_num_jobs(void)