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SubjectRe: [PATCH] fix idle ticks in cpu summary line of /proc/stat
On Mon, 12 Mar 2012 13:17:26 +0100
Michal Hocko <mhocko@suse.cz> wrote:

> Goot catch. But I think that the following fix should be better because
> it doesn't change the semantic of the function. What do you think?
..
> diff --git a/kernel/time/tick-sched.c b/kernel/time/tick-sched.c
> index 7656642..dec767f 100644
> --- a/kernel/time/tick-sched.c
> +++ b/kernel/time/tick-sched.c
> @@ -221,7 +221,7 @@ u64 get_cpu_idle_time_us(int cpu, u64 *last_update_time)
> update_ts_time_stats(cpu, ts, now, last_update_time);
> idle = ts->idle_sleeptime;
> } else {
> - if (ts->idle_active && !nr_iowait_cpu(cpu)) {
> + if (cpu_online(cpu) && ts->idle_active && !nr_iowait_cpu(cpu)) {
> ktime_t delta = ktime_sub(now, ts->idle_entrytime);
>
> idle = ktime_add(ts->idle_sleeptime, delta);
> @@ -262,7 +262,7 @@ u64 get_cpu_iowait_time_us(int cpu, u64 *last_update_time)
> update_ts_time_stats(cpu, ts, now, last_update_time);
> iowait = ts->iowait_sleeptime;
> } else {
> - if (ts->idle_active && nr_iowait_cpu(cpu) > 0) {
> + if (cpu_online(cpu) && ts->idle_active && nr_iowait_cpu(cpu) > 0) {
> ktime_t delta = ktime_sub(now, ts->idle_entrytime);
>
> iowait = ktime_add(ts->iowait_sleeptime, delta);

I would prefer an early exit from the functions. The target cpu is offline,
who guarantees that the "struct tick_sched" for the cpu contains anything
useful?

--
blue skies,
Martin.

"Reality continues to ruin my life." - Calvin.




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