Messages in this thread | | | Subject | Re: [PATCH] Track accurate idle time with tick_sched.idle_sleeptime | From | Andi Kleen <> | Date | 02 Sep 2007 00:23:53 +0200 |
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Venki Pallipadi <venkatesh.pallipadi@intel.com> writes: > > +void tick_nohz_stop_idle(int cpu) > +{ > + struct tick_sched *ts = &per_cpu(tick_cpu_sched, cpu); > + > + if (ts->idle_active) { > + ktime_t now, delta; > + now = ktime_get();
That could be PM timer read costing thousands of cycles.
For going into idle it's probably not a real problem, but it could seriously affect out of idle latencies.
You would really need a cheaper per CPU timer that doesn't stop in idle (which rules out sched_clock). It's all unfortunately quite messy.
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