nohz: Fix update_ts_time_stat idle accounting
update_ts_time_stat currently updates idle time even if we are in iowait loop at the moment. The only real users of the idle counter (via get_cpu_idle_time_us) are CPU governors and they expect to get cumulative time for both idle and iowait times. The value (idle_sleeptime) is also printed to userspace by print_cpu but it prints both idle and iowait times so the idle part is misleading. Let's clean this up and fix update_ts_time_stat to account both counters properly and update consumers of idle to consider iowait time as well. If we do this we might use get_cpu_{idle,iowait}_time_us from other contexts as well and we will get expected values. 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/e9c909c221a8da402c4da07e4cd968c3218f8eb1.1314172057.git.mhocko@suse.cz Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
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@ -120,10 +120,12 @@ static inline cputime64_t get_cpu_idle_time_jiffy(unsigned int cpu,
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static inline cputime64_t get_cpu_idle_time(unsigned int cpu, cputime64_t *wall)
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{
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u64 idle_time = get_cpu_idle_time_us(cpu, wall);
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u64 idle_time = get_cpu_idle_time_us(cpu, NULL);
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if (idle_time == -1ULL)
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return get_cpu_idle_time_jiffy(cpu, wall);
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else
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idle_time += get_cpu_iowait_time_us(cpu, wall);
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return idle_time;
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}
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@ -144,10 +144,12 @@ static inline cputime64_t get_cpu_idle_time_jiffy(unsigned int cpu,
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static inline cputime64_t get_cpu_idle_time(unsigned int cpu, cputime64_t *wall)
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{
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u64 idle_time = get_cpu_idle_time_us(cpu, wall);
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u64 idle_time = get_cpu_idle_time_us(cpu, NULL);
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if (idle_time == -1ULL)
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return get_cpu_idle_time_jiffy(cpu, wall);
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else
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idle_time += get_cpu_iowait_time_us(cpu, wall);
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return idle_time;
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}
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@ -159,9 +159,10 @@ update_ts_time_stats(int cpu, struct tick_sched *ts, ktime_t now, u64 *last_upda
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if (ts->idle_active) {
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delta = ktime_sub(now, ts->idle_entrytime);
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ts->idle_sleeptime = ktime_add(ts->idle_sleeptime, delta);
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if (nr_iowait_cpu(cpu) > 0)
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ts->iowait_sleeptime = ktime_add(ts->iowait_sleeptime, delta);
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else
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ts->idle_sleeptime = ktime_add(ts->idle_sleeptime, delta);
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ts->idle_entrytime = now;
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}
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@ -200,8 +201,7 @@ static ktime_t tick_nohz_start_idle(int cpu, struct tick_sched *ts)
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* @last_update_time: variable to store update time in
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*
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* Return the cummulative idle time (since boot) for a given
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* CPU, in microseconds. The idle time returned includes
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* the iowait time (unlike what "top" and co report).
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* CPU, in microseconds.
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*
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* This time is measured via accounting rather than sampling,
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* and is as accurate as ktime_get() is.
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@ -221,7 +221,7 @@ u64 get_cpu_idle_time_us(int cpu, u64 *last_update_time)
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}
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EXPORT_SYMBOL_GPL(get_cpu_idle_time_us);
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/*
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/**
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* get_cpu_iowait_time_us - get the total iowait time of a cpu
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* @cpu: CPU number to query
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* @last_update_time: variable to store update time in
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