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authorDenys Vlasenko2010-08-16 02:49:21 +0200
committerDenys Vlasenko2010-08-16 02:49:21 +0200
commitc9b9750a0e2a85d3d045cc8d0217d4605f2d7989 (patch)
tree00168254b5f9e960ce42ea36d6d4a78bd269eae4 /libbb/get_cpu_count.c
parenta4160e15ec866005f3ad30c967bc4829fbb1c8e3 (diff)
downloadbusybox-c9b9750a0e2a85d3d045cc8d0217d4605f2d7989.zip
busybox-c9b9750a0e2a85d3d045cc8d0217d4605f2d7989.tar.gz
libbb: factor out common code from mpstat/iostat
Signed-off-by: Denys Vlasenko <vda.linux@googlemail.com>
Diffstat (limited to 'libbb/get_cpu_count.c')
-rw-r--r--libbb/get_cpu_count.c47
1 files changed, 47 insertions, 0 deletions
diff --git a/libbb/get_cpu_count.c b/libbb/get_cpu_count.c
new file mode 100644
index 0000000..a0dcb45
--- /dev/null
+++ b/libbb/get_cpu_count.c
@@ -0,0 +1,47 @@
+/* vi: set sw=4 ts=4: */
+/*
+ * Factored out of mpstat/iostat.
+ *
+ * Copyright (C) 2010 Marek Polacek <mmpolacek@gmail.com>
+ *
+ * Licensed under GPLv2, see file License in this tarball for details.
+ */
+#include "libbb.h"
+
+/* Does str start with "cpu"? */
+int FAST_FUNC starts_with_cpu(const char *str)
+{
+ return ((str[0] - 'c') | (str[1] - 'p') | (str[2] - 'u')) == 0;
+}
+
+/*
+ * Get number of processors. Uses /proc/stat.
+ * Return value 0 means one CPU and non SMP kernel.
+ * Otherwise N means N processor(s) and SMP kernel.
+ */
+unsigned FAST_FUNC get_cpu_count(void)
+{
+ FILE *fp;
+ char line[256];
+ int proc_nr = -1;
+
+ fp = xfopen_for_read("/proc/stat");
+ while (fgets(line, sizeof(line), fp)) {
+ if (!starts_with_cpu(line)) {
+ if (proc_nr >= 0)
+ break; /* we are past "cpuN..." lines */
+ continue;
+ }
+ if (line[3] != ' ') { /* "cpuN" */
+ int num_proc;
+ if (sscanf(line + 3, "%u", &num_proc) == 1
+ && num_proc > proc_nr
+ ) {
+ proc_nr = num_proc;
+ }
+ }
+ }
+
+ fclose(fp);
+ return proc_nr + 1;
+}