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authorMichal Hocko <mhocko@suse.cz>2011-08-24 09:40:25 +0200
committerThomas Gleixner <tglx@linutronix.de>2011-09-08 11:10:55 +0200
commita25cac5198d4ff2842ccca63b423962848ad24b2 (patch)
treeb1e476f78416e522bf27502349ab6ffebd3b6147 /kernel/time
parentnohz: Make idle/iowait counter update conditional (diff)
downloadlinux-a25cac5198d4ff2842ccca63b423962848ad24b2.tar.xz
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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things got more tricky because we are not doing idle/iowait accounting while we are tickless so the value might get outdated.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 <mhocko@suse.cz> Cc: Dave Jones <davej@redhat.com> Cc: Arnd Bergmann <arnd@arndb.de> Cc: Alexey Dobriyan <adobriyan@gmail.com> Link: http://lkml.kernel.org/r/39181366adac1b39cb6aa3cd53ff0f7c78d32676.1314172057.git.mhocko@suse.cz Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Diffstat (limited to 'kernel/time')
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