On Mon, Dec 17, 2018 at 6:58 AM Peter Zijlstra <peterz@xxxxxxxxxxxxx> wrote: > > On Fri, Dec 14, 2018 at 09:15:05AM -0800, Suren Baghdasaryan wrote: > > Eliminate the idle mode and keep the worker doing 2s update intervals > > at all times. > > That sounds like a bad deal.. esp. so for battery powered devices like > say Andoird. > > In general the push has been to always idle everything, see NOHZ and > NOHZ_FULL and all the work that's being put into getting rid of any and > all period work. Thanks for the feedback Peter! The removal of idle mode is unfortunate but so far we could not find an elegant solution to handle 3 states (IDLE / REGULAR / POLLING) without additional synchronization inside the hotpath. The issue, as I remember it, was that while scheduling a regular update inside psi_group_change() (IDLE to REGULAR transition) we might override an earlier update being scheduled inside psi_update_work(). I think we can solve that by using mod_delayed_work_on() inside psi_update_work() but I might be missing some other race. I'll discuss this again with Johannes and see if we can synchronize all states using only atomic operations on clock_mode. > -- > You received this message because you are subscribed to the Google Groups "kernel-team" group. > To unsubscribe from this group and stop receiving emails from it, send an email to kernel-team+unsubscribe@xxxxxxxxxxx. >
