With this change, "iowait-ness" of every idle period is decided at the moment it starts: if this CPU's run-queue had tasks waiting on I/O, then this idle period's duration will be added to iowait_sleeptime.
This fixes the bug where iowait and/or idle counts could go backwards, but iowait accounting is not precise (it can show more iowait that there really is). Signed-off-by: Denys Vlasenko <[email protected]> Cc: Frederic Weisbecker <[email protected]> Cc: Hidetoshi Seto <[email protected]> Cc: Fernando Luis Vazquez Cao <[email protected]> Cc: Tetsuo Handa <[email protected]> Cc: Thomas Gleixner <[email protected]> Cc: Ingo Molnar <[email protected]> Cc: Peter Zijlstra <[email protected]> Cc: Andrew Morton <[email protected]> Cc: Arjan van de Ven <[email protected]> Cc: Oleg Nesterov <[email protected]> --- kernel/time/tick-sched.c | 8 ++++---- 1 file changed, 4 insertions(+), 4 deletions(-) diff --git a/kernel/time/tick-sched.c b/kernel/time/tick-sched.c index 8f0f2ee..47ed7cf 100644 --- a/kernel/time/tick-sched.c +++ b/kernel/time/tick-sched.c @@ -413,7 +413,7 @@ static void tick_nohz_stop_idle(struct tick_sched *ts, ktime_t now) /* Updates the per cpu time idle statistics counters */ write_seqcount_begin(&ts->idle_sleeptime_seq); delta = ktime_sub(now, ts->idle_entrytime); - if (nr_iowait_cpu(smp_processor_id()) > 0) + if (ts->idle_active == 2) ts->iowait_sleeptime = ktime_add(ts->iowait_sleeptime, delta); else ts->idle_sleeptime = ktime_add(ts->idle_sleeptime, delta); @@ -429,7 +429,7 @@ static ktime_t tick_nohz_start_idle(struct tick_sched *ts) write_seqcount_begin(&ts->idle_sleeptime_seq); ts->idle_entrytime = now; - ts->idle_active = 1; + ts->idle_active = nr_iowait_cpu(smp_processor_id()) ? 2 : 1; write_seqcount_end(&ts->idle_sleeptime_seq); sched_clock_idle_sleep_event(); @@ -469,7 +469,7 @@ u64 get_cpu_idle_time_us(int cpu, u64 *last_update_time) seq = read_seqcount_begin(&ts->idle_sleeptime_seq); idle = ts->idle_sleeptime; - if (ts->idle_active && !nr_iowait_cpu(cpu)) { + if (ts->idle_active == 1) { delta = ktime_sub(now, ts->idle_entrytime); idle = ktime_add(idle, delta); } @@ -511,7 +511,7 @@ u64 get_cpu_iowait_time_us(int cpu, u64 *last_update_time) seq = read_seqcount_begin(&ts->idle_sleeptime_seq); iowait = ts->iowait_sleeptime; - if (ts->idle_active && nr_iowait_cpu(cpu) > 0) { + if (ts->idle_active == 2) { delta = ktime_sub(now, ts->idle_entrytime); iowait = ktime_add(ts->iowait_sleeptime, delta); } -- 1.8.1.4 -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to [email protected] More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
