From: Wanpeng Li <kernellwp@gmail.com>
To: Steven Rostedt <rostedt@goodmis.org>,
"pang.xunlei" <pang.xunlei@linaro.org>
Cc: linux-kernel@vger.kernel.org, Ingo Molnar <mingo@redhat.com>,
Peter Zijlstra <peterz@infradead.org>,
Juri Lelli <juri.lelli@gmail.com>
Subject: Re: [PATCH v2 5/6] sched/dl: Optimize select_task_rq_dl() for non-DL curr task
Date: Wed, 05 Nov 2014 07:33:40 +0800 [thread overview]
Message-ID: <54596254.6090401@gmail.com> (raw)
In-Reply-To: <20141104094549.59acebb6@gandalf.local.home>
Hi Steven,
On 14/11/4 下午10:45, Steven Rostedt wrote:
> On Tue, 4 Nov 2014 19:13:04 +0800
> "pang.xunlei" <pang.xunlei@linaro.org> 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 <pang.xunlei@linaro.org>
>> ---
>> 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)
> --
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next prev parent reply other threads:[~2014-11-04 23:33 UTC|newest]
Thread overview: 17+ messages / expand[flat|nested] mbox.gz Atom feed top
2014-11-04 11:13 [PATCH v2 1/6] sched/cpupri: Deal with cpupri.pri_to_cpu[CPUPRI_IDLE] for idle cases pang.xunlei
2014-11-04 11:13 ` [PATCH v2 2/6] sched/rt: Optimize select_task_rq_rt() for non-RT curr task pang.xunlei
2014-11-04 12:52 ` Steven Rostedt
2014-11-04 14:29 ` pang.xunlei
2014-11-04 14:47 ` Steven Rostedt
2014-11-04 15:09 ` pang.xunlei
2014-11-04 11:13 ` [PATCH v2 3/6] sched/cpupri: Remove unnecessary definitions in cpupri.h pang.xunlei
2014-11-04 14:39 ` Steven Rostedt
2014-11-04 11:13 ` [PATCH v2 4/6] sched/dl: Modify cpudl_find() for more cases of electing best_cpu pang.xunlei
2014-11-04 11:13 ` [PATCH v2 5/6] sched/dl: Optimize select_task_rq_dl() for non-DL curr task pang.xunlei
2014-11-04 11:24 ` Wanpeng Li
2014-11-04 14:19 ` pang.xunlei
2014-11-04 23:30 ` Wanpeng Li
2014-11-04 14:45 ` Steven Rostedt
2014-11-04 15:11 ` Peter Zijlstra
2014-11-04 23:33 ` Wanpeng Li [this message]
2014-11-04 11:13 ` [PATCH v2 6/6] sched/dl: Remove unnecessary definitions in cpudeadline.h pang.xunlei
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