linux-kernel - Re: [RFC PATCH 0/2] sched: simplify the select_task_rq

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Message-ID: <50FFACC5.7060405@linux.vnet.ibm.com>
Date:	Wed, 23 Jan 2013 17:26:29 +0800
From:	Michael Wang <wangyun@...ux.vnet.ibm.com>
To:	Mike Galbraith <bitbucket@...ine.de>
CC:	linux-kernel@...r.kernel.org, mingo@...hat.com,
	peterz@...radead.org, mingo@...nel.org, a.p.zijlstra@...llo.nl
Subject: Re: [RFC PATCH 0/2] sched: simplify the select_task_rq_fair()

On 01/23/2013 05:18 PM, Mike Galbraith wrote:
> On Wed, 2013-01-23 at 17:00 +0800, Michael Wang wrote: 
>> On 01/23/2013 04:49 PM, Mike Galbraith wrote:
>>> On Wed, 2013-01-23 at 16:30 +0800, Michael Wang wrote: 
>>>> On 01/23/2013 04:20 PM, Mike Galbraith wrote:
>>>>> On Wed, 2013-01-23 at 15:10 +0800, Michael Wang wrote: 
>>>>>> On 01/23/2013 02:28 PM, Mike Galbraith wrote:
>>>>>
>>>>>>> Abbreviated test run:
>>>>>>> Tasks    jobs/min  jti  jobs/min/task      real       cpu
>>>>>>>   640   158044.01   81       246.9438     24.54    577.66   Wed Jan 23 07:14:33 2013
>>>>>>>  1280    50434.33   39        39.4018    153.80   5737.57   Wed Jan 23 07:17:07 2013
>>>>>>>  2560    47214.07   34        18.4430    328.58  12715.56   Wed Jan 23 07:22:36 2013
>>>>>>
>>>>>> So still not works... and not going to balance path while waking up will
>>>>>> fix it, looks like that's the only choice if no error on balance path
>>>>>> could be found...benchmark wins again, I'm feeling bad...
>>>>>>
>>>>>> I will conclude the info we collected and make a v3 later.
>>>>>
>>>>> FWIW, I hacked virgin to do full balance if an idle CPU was not found,
>>>>> leaving the preference to wake cache affine intact though, turned on
>>>>> WAKE_BALANCE in all domains, and it did not collapse.  In fact, the high
>>>>> load end, where the idle search will frequently be a waste of cycles,
>>>>> actually improved a bit.  Things that make ya go hmmm.
>>>>
>>>> Oh, does that means the old balance path is good while the new is really
>>>> broken, I mean, compared this with the previously results, could we say
>>>> that all the collapse was just caused by the change of balance path?
>>>
>>> That's a good supposition.  I'll see if it holds.
>>
>> I just notice that there is no sd support the WAKE flag at all according
>> to your debug info, isn't it?
> 
> There is, I turned it on in all domains.

So is the debug info show the changes? May be I missed some timing which
need to rebuild the sbm.

Regards,
Michael Wang

> 
> -Mike
> 

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