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 16:24:48 +0800 [thread overview]
Message-ID: <510A2A50.1090207@linux.vnet.ibm.com> (raw)
In-Reply-To: <87pq0lu7ew.fsf@sejong.aot.lge.com>
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...
Regards,
Michael Wang
>
> Thanks,
> Namhyung
> --
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next prev parent reply other threads:[~2013-01-31 8:25 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 [this message]
2013-01-31 8:45 ` Michael Wang
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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