On Wed, Jun 04, 2014 at 02:09:18PM +0100, Morten Rasmussen wrote: > On Wed, Jun 04, 2014 at 12:52:46PM +0100, Vincent Guittot wrote: > > On 4 June 2014 13:23, Morten Rasmussen <morten.rasmus...@arm.com> wrote: > > > I get: > > > > > > A: 15/40 ms = 37.5% > > > B: 20/40 ms = 50% > > > > > > Schedule: > > > > > > | 5 ms | 5 ms | 5 ms | 5 ms | 5 ms | 5 ms | 5 ms | 5 ms | 5 ms | > > > A: run rq run ----------- sleeping ------------- run > > > B: rq run rq run ---- sleeping ------------- rq > > > > > >> and CPU runnable will be 60% too > > > > > > rq->avg.runnable_avg_sum should be 50%. You have two tasks running for > > > 20 ms every 40 ms. > > > > > > Right? > > > > ok, i see the misunderstood. > > it's depends of what we mean by runnable. You take the % of time > > whereas i take the runnable_avg_sum/period > > Right. There is a difference. > > > > > so A is on_rq 15/40 ms = 37.5% of the time which gives a > > runnable_avg_sum/runnable_avg_period of 47% > > B is on_rq 20/40 ms = 50% of the time which gives a > > runnable_avg_sum/runnable_avg_period of 60% > > and CPU has a task on its rq 20/40ms = 50% of the time which gives a > > runnable_avg_sum/runnable_avg_period of 60% > > Yes, that seems about right.
If my calculations are right, cfs.runnable_load_avg would peak 15 ms into the period at about 104%. After 20 ms A has decayed more than B has gained so the sum is slightly lower. -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majord...@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
