linux-kernel - Re: [PATCH 2/2] sched/deadline: don't need to balance during wakeup if wakee is pinned

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Date:	Tue, 21 Oct 2014 21:39:26 +0800
From:	Wanpeng Li <kernellwp@...il.com>
To:	Juri Lelli <juri.lelli@....com>,
	Wanpeng Li <wanpeng.li@...ux.intel.com>,
	Ingo Molnar <mingo@...hat.com>,
	Peter Zijlstra <peterz@...radead.org>
CC:	"linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH 2/2] sched/deadline: don't need to balance during wakeup
 if wakee is pinned

Hi Juri,

于 10/21/14, 9:29 PM, Juri Lelli 写道:
> Hi,
>
> On 21/10/14 13:19, Wanpeng Li wrote:
>> Cc Juri,
>>
>> 于 10/14/14, 10:22 AM, Wanpeng Li 写道:
>>> Use nr_cpus_allowed to bail from select_task_rq() when only one cpu
>>> can be used, and saves some cycles for pinned tasks.
>>>
>>> Signed-off-by: Wanpeng Li <wanpeng.li@...ux.intel.com>
>>> ---
>>>   kernel/sched/deadline.c | 3 +++
>>>   1 file changed, 3 insertions(+)
>>>
>>> diff --git a/kernel/sched/deadline.c b/kernel/sched/deadline.c
>>> index f46b7f1..5874bf8 100644
>>> --- a/kernel/sched/deadline.c
>>> +++ b/kernel/sched/deadline.c
>>> @@ -914,6 +914,9 @@ 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;
>>> +
>>>   	if (sd_flag != SD_BALANCE_WAKE)
>>>   		goto out;
>>>
> Apart from the encoding of the resend, it looks good, thanks!

What's your meaning of resend? Do you mean this one?

https://lkml.org/lkml/2014/10/10/425

I'm afraid they are different patches.

Regards,
Wanpeng Li

>
> Best,
>
> - Juri
>

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