From: Michal Hocko Date: Wed, 24 Aug 2011 07:40:25 +0000 (+0200) Subject: proc: Consider NO_HZ when printing idle and iowait times X-Git-Tag: v3.2-rc1~160^2~11 X-Git-Url: http://git.openpandora.org/cgi-bin/gitweb.cgi?a=commitdiff_plain;h=a25cac5198d4;p=pandora-kernel.git proc: Consider NO_HZ when printing idle and iowait times show_stat handler of the /proc/stat file relies on kstat_cpu(cpu) statistics when priting information about idle and iowait times. This is OK if we are not using tickless kernel (CONFIG_NO_HZ) because counters are updated periodically. With NO_HZ things got more tricky because we are not doing idle/iowait accounting while we are tickless so the value might get outdated. Users of /proc/stat will notice that by unchanged idle/iowait values which is then interpreted as 0% idle/iowait time. From the user space POV this is an unexpected behavior and a change of the interface. Let's fix this by using get_cpu_{idle,iowait}_time_us which accounts the total idle/iowait time since boot and it doesn't rely on sampling or any other periodic activity. Fall back to the previous behavior if NO_HZ is disabled or not configured. Signed-off-by: Michal Hocko Cc: Dave Jones Cc: Arnd Bergmann Cc: Alexey Dobriyan Link: http://lkml.kernel.org/r/39181366adac1b39cb6aa3cd53ff0f7c78d32676.1314172057.git.mhocko@suse.cz Signed-off-by: Thomas Gleixner --- Reading git-diff-tree failed