From: Michael Wang <wangyun@linux.vnet.ibm.com>
To: Namhyung Kim <namhyung@kernel.org>
Cc: Sebastian Andrzej Siewior <bigeasy@linutronix.de>,
linux-kernel@vger.kernel.org,
"Rafael J. Wysocki" <rafael.j.wysocki@intel.com>,
Ingo Molnar <mingo@redhat.com>,
Peter Zijlstra <peterz@infradead.org>,
tglx@linutronix.de
Subject: Re: [RFC 2/2] sched/fair: prefer a CPU in the "lowest" idle state
Date: Thu, 31 Jan 2013 16:45:54 +0800 [thread overview]
Message-ID: <510A2F42.5050007@linux.vnet.ibm.com> (raw)
In-Reply-To: <510A2A50.1090207@linux.vnet.ibm.com>
On 01/31/2013 04:24 PM, Michael Wang wrote:
> On 01/31/2013 03:40 PM, Namhyung Kim wrote:
>> On Thu, 31 Jan 2013 15:30:02 +0800, Michael Wang wrote:
>>> On 01/31/2013 02:58 PM, Namhyung Kim wrote:
>>>> But AFAIK the number of states in cpuidle is usually less than 10 so maybe
>>>> we can change the weight then, but there's no promise...
>>>
>>> And I just got another case we should take care:
>>>
>>> group 0 cpu 0 cpu 1
>>> power index 8 power index 8
>>>
>>>
>>> group 1 cpu 2 cpu 3
>>> power index 0 load 15
>>>
>>> so load of group 0 is 16 and group 1 is 15, but group 0 is better...
>>
>> Maybe it's not. The cpus in group 0 are in a lower power state so that
>> there will be a benefit to select cpu 2 from the power' PoV IMHO. Also
>> such a low power state has a longer exit latency so that we should
>> choose cpu2 to get a better performance and it's the basic idea of this
>> patchset I believe.
>
> Well, this case is just to notify that, we may face the comparison
> between load and index, not between index and index, I just doubt there
> won't be a rule which could take care both, besides, comparison between
> load and index is strange...
Oh, I miss the point that you call it 'idle load', hmm...may be it could
works, if we could scale the current load number, then we will have more
'space' for 'idle load'.
Regards,
Michael Wang
>
> Regards,
> Michael Wang
>
>>
>> Thanks,
>> Namhyung
>> --
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>
next prev parent reply other threads:[~2013-01-31 8:46 UTC|newest]
Thread overview: 17+ messages / expand[flat|nested] mbox.gz Atom feed top
2013-01-30 21:19 [RFC] Consider CPU idle state while choosing a new CPU Sebastian Andrzej Siewior
2013-01-30 21:19 ` [RFC 1/2] cpuidle: trace state of the CPU Sebastian Andrzej Siewior
2013-01-31 5:21 ` Namhyung Kim
2013-02-02 17:35 ` Sebastian Andrzej Siewior
2013-01-30 21:19 ` [RFC 2/2] sched/fair: prefer a CPU in the "lowest" idle state Sebastian Andrzej Siewior
2013-01-31 2:12 ` Michael Wang
2013-01-31 5:16 ` Namhyung Kim
2013-01-31 6:39 ` Michael Wang
2013-01-31 6:58 ` Namhyung Kim
2013-01-31 7:30 ` Michael Wang
2013-01-31 7:40 ` Namhyung Kim
2013-01-31 8:24 ` Michael Wang
2013-01-31 8:45 ` Michael Wang [this message]
2013-01-31 8:57 ` Michael Wang
2013-02-01 8:53 ` Namhyung Kim
2013-02-02 17:50 ` Sebastian Andrzej Siewior
2013-02-04 3:01 ` Michael Wang
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