On Fri, 24 Jul 2020 at 18:34, Vincent Guittot <[email protected]> wrote: > > 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 Indeed, the complexity is not worth. Thanks for the explanation.
Regards, Jiang > > > > > Thanks a lot. > > > > Regards, > > Jiang
