Prior to this commit, the cpu idle and iowait data in /proc/stat were cleared when a CPU goes down. When the CPU came back online, both idle and iowait times were restarted from 0.
This commit preserves the CPU's idle and iowait values when a CPU goes offline and comes back online. Signed-off-by: Tom Hromatka <[email protected]> --- kernel/time/tick-sched.c | 9 +++++++++ 1 file changed, 9 insertions(+) diff --git a/kernel/time/tick-sched.c b/kernel/time/tick-sched.c index f0199a4ba1ad..4fbf67171dde 100644 --- a/kernel/time/tick-sched.c +++ b/kernel/time/tick-sched.c @@ -1383,13 +1383,22 @@ void tick_setup_sched_timer(void) void tick_cancel_sched_timer(int cpu) { struct tick_sched *ts = &per_cpu(tick_cpu_sched, cpu); + ktime_t idle_sleeptime, iowait_sleeptime; # ifdef CONFIG_HIGH_RES_TIMERS if (ts->sched_timer.base) hrtimer_cancel(&ts->sched_timer); # endif + /* + * Preserve idle and iowait sleep times accross a CPU offline/online + * sequence as they are accumulative. + */ + idle_sleeptime = ts->idle_sleeptime; + iowait_sleeptime = ts->iowait_sleeptime; memset(ts, 0, sizeof(*ts)); + ts->idle_sleeptime = idle_sleeptime; + ts->iowait_sleeptime = iowait_sleeptime; } #endif -- 2.25.4
