diff options
author | Michal Hocko <mhocko@suse.cz> | 2011-08-24 09:40:25 +0200 |
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committer | Thomas Gleixner <tglx@linutronix.de> | 2011-09-08 11:10:55 +0200 |
commit | a25cac5198d4ff2842ccca63b423962848ad24b2 (patch) | |
tree | b1e476f78416e522bf27502349ab6ffebd3b6147 /arch | |
parent | 09a1d34f8535ecf9a347ea76f7597730c2bc0c8d (diff) |
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accounting while we are tickless so the value might get outdated.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 'arch')
0 files changed, 0 insertions, 0 deletions