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 14:29:26 +0100
From:	Juri Lelli <juri.lelli@....com>
To:	Wanpeng Li <kernellwp@...il.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,

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!

Best,

- Juri

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