[Powertop] [PATCH] cpufreq: only try to open files under cpuX

There are called many useless 'open' syscalls that always fail, like: open("/sys/devices/system/cpu/uevent/cpufreq/scaling_governor", O_RDONLY) = -1 ENOTDIR (Not a directory) This patch filters this to /sys/devices/system/cpu/cpuX, where X is string starting with digit (from kernel sources it seems that X can only be integer). For match cases it will add only small overhead. Originally reported as: https://bugzilla.redhat.com/show_bug.cgi?id=886185 Signed-off-by: Jaroslav Škarvada <jskarvad(a)redhat.com&gt; --- src/tuning/cpufreq.cpp | 3 ++- 1 file changed, 2 insertions(+), 1 deletion(-) diff --git a/src/tuning/cpufreq.cpp b/src/tuning/cpufreq.cpp index df245ad..c448f4c 100644 --- a/src/tuning/cpufreq.cpp +++ b/src/tuning/cpufreq.cpp @@ -36,6 +36,7 @@ #include <dirent.h> #include <errno.h> #include <sys/stat.h> +#include <ctype.h> #include "../lib.h" #include "cpufreq.h" @@ -72,7 +73,7 @@ int cpufreq_tunable::good_bad(void) return ret; while ((dirent = readdir(dir))) { - if (dirent->d_name[0]=='.') + if (strlen(dirent->d_name) < 4 || strncmp(dirent->d_name, "cpu", 3) != 0 || !isdigit(dirent->d_name[3])) continue; sprintf(filename, "/sys/devices/system/cpu/%s/cpufreq/scaling_governor", dirent->d_name); file = fopen(filename, "r"); -- 1.7.11.7