Messages in this thread Patch in this message | | | Date | Mon, 7 Dec 2020 19:05:18 +0100 | From | Peter Zijlstra <> | Subject | Re: [RFC PATCH v5] sched/fair: select idle cpu from idle cpumask for task wakeup |
| |
On Mon, Dec 07, 2020 at 04:52:24PM +0000, Valentin Schneider wrote: > > On 07/12/20 15:48, Peter Zijlstra wrote: > > On Wed, Nov 18, 2020 at 12:31:13PM +0800, Aubrey Li wrote: > >> diff --git a/kernel/sched/idle.c b/kernel/sched/idle.c > >> index f324dc36fc43..6f5947673e66 100644 > >> --- a/kernel/sched/idle.c > >> +++ b/kernel/sched/idle.c > >> @@ -163,6 +163,7 @@ static void cpuidle_idle_call(void) > >> */ > >> > >> if (cpuidle_not_available(drv, dev)) { > >> + update_idle_cpumask(this_rq(), true); > >> tick_nohz_idle_stop_tick(); > >> > >> default_idle_call(); > >> @@ -193,6 +194,7 @@ static void cpuidle_idle_call(void) > >> max_latency_ns = dev->forced_idle_latency_limit_ns; > >> } > >> > >> + update_idle_cpumask(this_rq(), true); > >> tick_nohz_idle_stop_tick(); > >> > >> next_state = cpuidle_find_deepest_state(drv, dev, max_latency_ns); > >> @@ -205,10 +207,12 @@ static void cpuidle_idle_call(void) > >> */ > >> next_state = cpuidle_select(drv, dev, &stop_tick); > >> > >> - if (stop_tick || tick_nohz_tick_stopped()) > >> + if (stop_tick || tick_nohz_tick_stopped()) { > >> + update_idle_cpumask(this_rq(), true); > >> tick_nohz_idle_stop_tick(); > > > > We already have a callback in tick_nohz_idle_stop_tick(), namely > > nohz_balance_enter_idle(). > > That's a no-op for !NO_HZ_COMMON though. For similar reasons, Aubrey moved > the clearing of the cpumask to scheduler_tick(). > > Are you saying this mechanism should only be driven for NO_HZ kernels?
IFF it keys off of the tick being stopped, then yes. But as said in the other email, I think that's a very dubious thing to begin with.
| |