Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1752682AbaKDXdt (ORCPT ); Tue, 4 Nov 2014 18:33:49 -0500 Received: from mail-pa0-f51.google.com ([209.85.220.51]:42119 "EHLO mail-pa0-f51.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752492AbaKDXdr (ORCPT ); Tue, 4 Nov 2014 18:33:47 -0500 Message-ID: <54596254.6090401@gmail.com> Date: Wed, 05 Nov 2014 07:33:40 +0800 From: Wanpeng Li User-Agent: Mozilla/5.0 (Macintosh; Intel Mac OS X 10.10; rv:24.0) Gecko/20100101 Thunderbird/24.2.0 MIME-Version: 1.0 To: Steven Rostedt , "pang.xunlei" CC: linux-kernel@vger.kernel.org, Ingo Molnar , Peter Zijlstra , Juri Lelli Subject: Re: [PATCH v2 5/6] sched/dl: Optimize select_task_rq_dl() for non-DL curr task References: <1415099585-31174-1-git-send-email-pang.xunlei@linaro.org> <1415099585-31174-5-git-send-email-pang.xunlei@linaro.org> <20141104094549.59acebb6@gandalf.local.home> In-Reply-To: <20141104094549.59acebb6@gandalf.local.home> Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: 8bit Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Hi Steven, On 14/11/4 下午10:45, Steven Rostedt wrote: > On Tue, 4 Nov 2014 19:13:04 +0800 > "pang.xunlei" wrote: > >> When selecting the cpu for a waking DL task, if curr is a non-DL >> task which is bound only on this cpu, then we can give it a chance >> to select a different cpu for this DL task to avoid curr starving. >> >> Signed-off-by: pang.xunlei >> --- >> kernel/sched/deadline.c | 14 ++++++++++---- >> 1 file changed, 10 insertions(+), 4 deletions(-) >> >> diff --git a/kernel/sched/deadline.c b/kernel/sched/deadline.c >> index 7b0b2d2..1f64d4a 100644 >> --- a/kernel/sched/deadline.c >> +++ b/kernel/sched/deadline.c >> @@ -954,6 +954,9 @@ select_task_rq_dl(struct task_struct *p, int cpu, int sd_flag, int flags) >> struct task_struct *curr; >> struct rq *rq; >> >> + if (p->nr_cpus_allowed == 1) >> + goto out; >> + > This looks fine, and I'm wondering if we shouldn't just move this into > kernel/sched/core.c: select_task_rq(). Why bother calling the select_rq > code if the task is pinned? > > This change will make fair.c, rt.c, and deadline.c all start with the > same logic. If this should be an optimization, just move it to core.c > and be done with it. Actually I have already do this for dl class and patch merged in tip tree currently, maybe pang.xunlei miss it. I will send a patch to move them all to core.c soon. Regards, Wanpeng Li > > >> if (sd_flag != SD_BALANCE_WAKE && sd_flag != SD_BALANCE_FORK) >> goto out; >> >> @@ -970,11 +973,14 @@ select_task_rq_dl(struct task_struct *p, int cpu, int sd_flag, int flags) >> * can!) we prefer to send it somewhere else. On the >> * other hand, if it has a shorter deadline, we >> * try to make it stay here, it might be important. >> + * >> + * If the current task on @p's runqueue is a non-DL task, >> + * and this task is bound on current runqueue, then try to >> + * see if we can wake this DL task up on a different runqueue, >> */ >> - if (unlikely(dl_task(curr)) && >> - (curr->nr_cpus_allowed < 2 || >> - !dl_entity_preempt(&p->dl, &curr->dl)) && >> - (p->nr_cpus_allowed > 1)) { >> + if (unlikely(curr->nr_cpus_allowed < 2) || >> + unlikely(dl_task(curr) && >> + !dl_entity_preempt(&p->dl, &curr->dl))) { > This has the same issue as the rt.c change. > > -- Steve > >> int target = find_later_rq(p); >> >> if (target != -1) > -- > 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/ -- 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/