On Fri, 24 Jul 2020 at 10:12, Jiang Biao <[email protected]> wrote: > > On Fri, 24 Jul 2020 at 15:24, Vincent Guittot > <[email protected]> wrote: > > > > On Fri, 24 Jul 2020 at 01:39, Jiang Biao <[email protected]> wrote: > > > > > > From: Jiang Biao <[email protected]> > > > > > > Sched-idle CPU has been considered in select_idle_cpu and > > > select_idle_smt, it also needs to be considered in select_idle_core to > > > be consistent and keep the same *idle* policy. > > > > In the case of select_idle_core, we are looking for a core that is > > fully idle but if one CPU of the core is running a sched_idle task, > > the core will not be idle and we might end up having the wakeup task > > on a CPU and a sched_idle task on another CPU of the core which is not > > what we want > Got it. sched_idle task may interfere its sibling, which brings me > another question, > If there's a core with smt1 running sched_idle task and smt2 idle, > selecting smt1 > rather than smt2 should be more helpful for wakee task, because wakee task > could suppress the sched_idle task without neighbour interfering.
But the sched_idle will then probably quickly move on the idle smt2 > And there seems to be no consideration about that currently. > Is it worth improving that? This will complexify and extend the duration of the search loop and as mentioned above, it will most probably be a nop at the end because of sched_idle task moving on smt2 > > Thanks a lot. > > Regards, > Jiang
