* [PATCH]sched: convert wall-time to vruntime for check_preempt_tick @ 2011-04-07 12:43 Shaohua Li 2011-04-07 13:34 ` Mike Galbraith 0 siblings, 1 reply; 6+ messages in thread From: Shaohua Li @ 2011-04-07 12:43 UTC (permalink / raw) To: linux-kernel; +Cc: mingo, zheng.z.yan In check_preempt_tick(), delta is vruntime and ideal_runtime is wall runtime. Comparing vruntime and ideal_runtime looks buggy. Signed-off-by: Shaohua Li <shaohua.li@intel.com> diff --git a/kernel/sched_fair.c b/kernel/sched_fair.c index 3f7ec9e..0b76e3a 100644 --- a/kernel/sched_fair.c +++ b/kernel/sched_fair.c @@ -1121,7 +1121,7 @@ check_preempt_tick(struct cfs_rq *cfs_rq, struct sched_entity *curr) if (delta < 0) return; - if (delta > ideal_runtime) + if (delta > calc_delta_fair(ideal_runtime, curr)) resched_task(rq_of(cfs_rq)->curr); } } ^ permalink raw reply related [flat|nested] 6+ messages in thread
* Re: [PATCH]sched: convert wall-time to vruntime for check_preempt_tick 2011-04-07 12:43 [PATCH]sched: convert wall-time to vruntime for check_preempt_tick Shaohua Li @ 2011-04-07 13:34 ` Mike Galbraith 2011-04-08 0:35 ` Shaohua Li 0 siblings, 1 reply; 6+ messages in thread From: Mike Galbraith @ 2011-04-07 13:34 UTC (permalink / raw) To: Shaohua Li; +Cc: linux-kernel, mingo, zheng.z.yan On Thu, 2011-04-07 at 20:43 +0800, Shaohua Li wrote: > In check_preempt_tick(), delta is vruntime and ideal_runtime is wall runtime. > Comparing vruntime and ideal_runtime looks buggy. Why is that buggy? It's a distance in units ns, ala wakeup_granularity, a number. This number just happens to be variable. > Signed-off-by: Shaohua Li <shaohua.li@intel.com> > > diff --git a/kernel/sched_fair.c b/kernel/sched_fair.c > index 3f7ec9e..0b76e3a 100644 > --- a/kernel/sched_fair.c > +++ b/kernel/sched_fair.c > @@ -1121,7 +1121,7 @@ check_preempt_tick(struct cfs_rq *cfs_rq, struct sched_entity *curr) > if (delta < 0) > return; > > - if (delta > ideal_runtime) > + if (delta > calc_delta_fair(ideal_runtime, curr)) > resched_task(rq_of(cfs_rq)->curr); > } > } > -- > To unsubscribe from this list: send the line "unsubscribe linux-kernel" in > the body of a message to majordomo@vger.kernel.org > More majordomo info at http://vger.kernel.org/majordomo-info.html > Please read the FAQ at http://www.tux.org/lkml/ ^ permalink raw reply [flat|nested] 6+ messages in thread
* Re: [PATCH]sched: convert wall-time to vruntime for check_preempt_tick 2011-04-07 13:34 ` Mike Galbraith @ 2011-04-08 0:35 ` Shaohua Li 2011-04-08 2:49 ` Mike Galbraith 0 siblings, 1 reply; 6+ messages in thread From: Shaohua Li @ 2011-04-08 0:35 UTC (permalink / raw) To: Mike Galbraith; +Cc: linux-kernel@vger.kernel.org, mingo@elte.hu, Yan, Zheng Z On Thu, 2011-04-07 at 21:34 +0800, Mike Galbraith wrote: > On Thu, 2011-04-07 at 20:43 +0800, Shaohua Li wrote: > > In check_preempt_tick(), delta is vruntime and ideal_runtime is wall runtime. > > Comparing vruntime and ideal_runtime looks buggy. > > Why is that buggy? It's a distance in units ns, ala wakeup_granularity, > a number. This number just happens to be variable. vruntime is scaled wall-time. In all other places we do the scale from my understanding. I'm wondering why not do it here. ^ permalink raw reply [flat|nested] 6+ messages in thread
* Re: [PATCH]sched: convert wall-time to vruntime for check_preempt_tick 2011-04-08 0:35 ` Shaohua Li @ 2011-04-08 2:49 ` Mike Galbraith 2011-04-08 4:55 ` Shaohua Li 0 siblings, 1 reply; 6+ messages in thread From: Mike Galbraith @ 2011-04-08 2:49 UTC (permalink / raw) To: Shaohua Li; +Cc: linux-kernel@vger.kernel.org, mingo@elte.hu, Yan, Zheng Z On Fri, 2011-04-08 at 08:35 +0800, Shaohua Li wrote: > On Thu, 2011-04-07 at 21:34 +0800, Mike Galbraith wrote: > > On Thu, 2011-04-07 at 20:43 +0800, Shaohua Li wrote: > > > In check_preempt_tick(), delta is vruntime and ideal_runtime is wall runtime. > > > Comparing vruntime and ideal_runtime looks buggy. > > > > Why is that buggy? It's a distance in units ns, ala wakeup_granularity, > > a number. This number just happens to be variable. > vruntime is scaled wall-time. In all other places we do the scale from > my understanding. I'm wondering why not do it here. The purpose was to ensure that there is not too much spread, just like wakeup preemption. Using the number that determines tick induced spread as the spread caliper seems perfectly fine to me. -Mike ^ permalink raw reply [flat|nested] 6+ messages in thread
* Re: [PATCH]sched: convert wall-time to vruntime for check_preempt_tick 2011-04-08 2:49 ` Mike Galbraith @ 2011-04-08 4:55 ` Shaohua Li 2011-04-08 5:31 ` Mike Galbraith 0 siblings, 1 reply; 6+ messages in thread From: Shaohua Li @ 2011-04-08 4:55 UTC (permalink / raw) To: Mike Galbraith; +Cc: linux-kernel@vger.kernel.org, mingo@elte.hu, Yan, Zheng Z On Fri, 2011-04-08 at 10:49 +0800, Mike Galbraith wrote: > On Fri, 2011-04-08 at 08:35 +0800, Shaohua Li wrote: > > On Thu, 2011-04-07 at 21:34 +0800, Mike Galbraith wrote: > > > On Thu, 2011-04-07 at 20:43 +0800, Shaohua Li wrote: > > > > In check_preempt_tick(), delta is vruntime and ideal_runtime is wall runtime. > > > > Comparing vruntime and ideal_runtime looks buggy. > > > > > > Why is that buggy? It's a distance in units ns, ala wakeup_granularity, > > > a number. This number just happens to be variable. > > vruntime is scaled wall-time. In all other places we do the scale from > > my understanding. I'm wondering why not do it here. > > The purpose was to ensure that there is not too much spread, just like > wakeup preemption. Using the number that determines tick induced spread > as the spread caliper seems perfectly fine to me. But we scale wakeup_granularity too for wakeup preemption, see wakeup_gran(), am I missing anything? ^ permalink raw reply [flat|nested] 6+ messages in thread
* Re: [PATCH]sched: convert wall-time to vruntime for check_preempt_tick 2011-04-08 4:55 ` Shaohua Li @ 2011-04-08 5:31 ` Mike Galbraith 0 siblings, 0 replies; 6+ messages in thread From: Mike Galbraith @ 2011-04-08 5:31 UTC (permalink / raw) To: Shaohua Li; +Cc: linux-kernel@vger.kernel.org, mingo@elte.hu, Yan, Zheng Z On Fri, 2011-04-08 at 12:55 +0800, Shaohua Li wrote: > On Fri, 2011-04-08 at 10:49 +0800, Mike Galbraith wrote: > > On Fri, 2011-04-08 at 08:35 +0800, Shaohua Li wrote: > > > On Thu, 2011-04-07 at 21:34 +0800, Mike Galbraith wrote: > > > > On Thu, 2011-04-07 at 20:43 +0800, Shaohua Li wrote: > > > > > In check_preempt_tick(), delta is vruntime and ideal_runtime is wall runtime. > > > > > Comparing vruntime and ideal_runtime looks buggy. > > > > > > > > Why is that buggy? It's a distance in units ns, ala wakeup_granularity, > > > > a number. This number just happens to be variable. > > > vruntime is scaled wall-time. In all other places we do the scale from > > > my understanding. I'm wondering why not do it here. > > > > The purpose was to ensure that there is not too much spread, just like > > wakeup preemption. Using the number that determines tick induced spread > > as the spread caliper seems perfectly fine to me. > But we scale wakeup_granularity too for wakeup preemption, see > wakeup_gran(), am I missing anything? Only because we want lighter tasks to be easier to preempt, and heavier tasks harder. Weight is already built into vruntime. -Mike ^ permalink raw reply [flat|nested] 6+ messages in thread
end of thread, other threads:[~2011-04-08 5:31 UTC | newest] Thread overview: 6+ messages (download: mbox.gz follow: Atom feed -- links below jump to the message on this page -- 2011-04-07 12:43 [PATCH]sched: convert wall-time to vruntime for check_preempt_tick Shaohua Li 2011-04-07 13:34 ` Mike Galbraith 2011-04-08 0:35 ` Shaohua Li 2011-04-08 2:49 ` Mike Galbraith 2011-04-08 4:55 ` Shaohua Li 2011-04-08 5:31 ` Mike Galbraith
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