From 09a1d34f8535ecf9a347ea76f7597730c2bc0c8d Mon Sep 17 00:00:00 2001 From: Michal Hocko Date: Wed, 24 Aug 2011 09:39:30 +0200 Subject: nohz: Make idle/iowait counter update conditional get_cpu_{idle,iowait}_time_us update idle/iowait counters unconditionally if the given CPU is in the idle loop. This doesn't work well outside of CPU governors which are singletons so nobody (except for IRQ) can race with them. We will need to use both functions from /proc/stat handler to properly handle nohz idle/iowait times. Make the update depend on a non NULL last_update_time argument. Signed-off-by: Michal Hocko Cc: Dave Jones Cc: Arnd Bergmann Cc: Alexey Dobriyan Link: http://lkml.kernel.org/r/11f23179472635ce52e78921d47a20216b872f23.1314172057.git.mhocko@suse.cz Signed-off-by: Thomas Gleixner --- kernel/time/tick-sched.c | 41 +++++++++++++++++++++++++++++++++++------ 1 file changed, 35 insertions(+), 6 deletions(-) diff --git a/kernel/time/tick-sched.c b/kernel/time/tick-sched.c index 7ab44bca6546..664c4a365439 100644 --- a/kernel/time/tick-sched.c +++ b/kernel/time/tick-sched.c @@ -198,7 +198,8 @@ static ktime_t tick_nohz_start_idle(int cpu, struct tick_sched *ts) /** * get_cpu_idle_time_us - get the total idle time of a cpu * @cpu: CPU number to query - * @last_update_time: variable to store update time in + * @last_update_time: variable to store update time in. Do not update + * counters if NULL. * * Return the cummulative idle time (since boot) for a given * CPU, in microseconds. @@ -211,20 +212,35 @@ static ktime_t tick_nohz_start_idle(int cpu, struct tick_sched *ts) u64 get_cpu_idle_time_us(int cpu, u64 *last_update_time) { struct tick_sched *ts = &per_cpu(tick_cpu_sched, cpu); + ktime_t now, idle; if (!tick_nohz_enabled) return -1; - update_ts_time_stats(cpu, ts, ktime_get(), last_update_time); + now = ktime_get(); + if (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)) { + ktime_t delta = ktime_sub(now, ts->idle_entrytime); + + idle = ktime_add(ts->idle_sleeptime, delta); + } else { + idle = ts->idle_sleeptime; + } + } + + return ktime_to_us(idle); - return ktime_to_us(ts->idle_sleeptime); } EXPORT_SYMBOL_GPL(get_cpu_idle_time_us); /** * get_cpu_iowait_time_us - get the total iowait time of a cpu * @cpu: CPU number to query - * @last_update_time: variable to store update time in + * @last_update_time: variable to store update time in. Do not update + * counters if NULL. * * Return the cummulative iowait time (since boot) for a given * CPU, in microseconds. @@ -237,13 +253,26 @@ EXPORT_SYMBOL_GPL(get_cpu_idle_time_us); u64 get_cpu_iowait_time_us(int cpu, u64 *last_update_time) { struct tick_sched *ts = &per_cpu(tick_cpu_sched, cpu); + ktime_t now, iowait; if (!tick_nohz_enabled) return -1; - update_ts_time_stats(cpu, ts, ktime_get(), last_update_time); + now = ktime_get(); + if (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) { + ktime_t delta = ktime_sub(now, ts->idle_entrytime); + + iowait = ktime_add(ts->iowait_sleeptime, delta); + } else { + iowait = ts->iowait_sleeptime; + } + } - return ktime_to_us(ts->iowait_sleeptime); + return ktime_to_us(iowait); } EXPORT_SYMBOL_GPL(get_cpu_iowait_time_us); -- cgit v1.2.3