Re: [PATCH] sched: Fix SCHED_HRTICK bug leading to late preemption of tasks

2016-09-19 Thread Wanpeng Li
2016-09-20 2:08 GMT+08:00 Joonwoo Park : > On Sun, Sep 18, 2016 at 07:28:32AM +0800, Wanpeng Li wrote: >> 2016-09-17 9:28 GMT+08:00 Joonwoo Park : >> > From: Srivatsa Vaddagiri >> > >> > SCHED_HRTICK feature is useful to preempt SCHED_FAIR tasks on-the-dot >> > (just when they would have exceeded

Re: [PATCH] sched: Fix SCHED_HRTICK bug leading to late preemption of tasks

2016-09-19 Thread Joonwoo Park
On Mon, Sep 19, 2016 at 11:04:49AM -0700, Joonwoo Park wrote: > On Mon, Sep 19, 2016 at 10:21:58AM +0200, Peter Zijlstra wrote: > > On Fri, Sep 16, 2016 at 06:28:51PM -0700, Joonwoo Park wrote: > > > From: Srivatsa Vaddagiri > > > > > > SCHED_HRTICK feature is useful to preempt SCHED_FAIR tasks o

Re: [PATCH] sched: Fix SCHED_HRTICK bug leading to late preemption of tasks

2016-09-19 Thread Joonwoo Park
On Sun, Sep 18, 2016 at 07:28:32AM +0800, Wanpeng Li wrote: > 2016-09-17 9:28 GMT+08:00 Joonwoo Park : > > From: Srivatsa Vaddagiri > > > > SCHED_HRTICK feature is useful to preempt SCHED_FAIR tasks on-the-dot > > (just when they would have exceeded their ideal_runtime). It makes use > > of a per-

Re: [PATCH] sched: Fix SCHED_HRTICK bug leading to late preemption of tasks

2016-09-19 Thread Joonwoo Park
On Mon, Sep 19, 2016 at 10:21:58AM +0200, Peter Zijlstra wrote: > On Fri, Sep 16, 2016 at 06:28:51PM -0700, Joonwoo Park wrote: > > From: Srivatsa Vaddagiri > > > > SCHED_HRTICK feature is useful to preempt SCHED_FAIR tasks on-the-dot > > Right, but I always found the overhead of the thing too h

Re: [PATCH] sched: Fix SCHED_HRTICK bug leading to late preemption of tasks

2016-09-19 Thread Peter Zijlstra
On Fri, Sep 16, 2016 at 06:28:51PM -0700, Joonwoo Park wrote: > From: Srivatsa Vaddagiri > > SCHED_HRTICK feature is useful to preempt SCHED_FAIR tasks on-the-dot Right, but I always found the overhead of the thing too high to be really useful. How come you're using this? > joonwoop: Do we a

Re: [PATCH] sched: Fix SCHED_HRTICK bug leading to late preemption of tasks

2016-09-17 Thread Wanpeng Li
2016-09-17 9:28 GMT+08:00 Joonwoo Park : > From: Srivatsa Vaddagiri > > SCHED_HRTICK feature is useful to preempt SCHED_FAIR tasks on-the-dot > (just when they would have exceeded their ideal_runtime). It makes use > of a per-cpu hrtimer resource and hence alarming that hrtimer should > be based o

[PATCH] sched: Fix SCHED_HRTICK bug leading to late preemption of tasks

2016-09-16 Thread Joonwoo Park
From: Srivatsa Vaddagiri SCHED_HRTICK feature is useful to preempt SCHED_FAIR tasks on-the-dot (just when they would have exceeded their ideal_runtime). It makes use of a per-cpu hrtimer resource and hence alarming that hrtimer should be based on total SCHED_FAIR tasks a cpu has across its variou