linux-kernel - Re: [RFC 2/2] sched/fair: prefer a CPU in the "lowest" idle state

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite: Windows password security audit tool. GUI, reports in PDF.

[<prev] [next>] [<thread-prev] [thread-next>] [day] [month] [year] [list]

Message-ID: <510A2F42.5050007@linux.vnet.ibm.com>
Date:	Thu, 31 Jan 2013 16:45:54 +0800
From:	Michael Wang <wangyun@...ux.vnet.ibm.com>
To:	Namhyung Kim <namhyung@...nel.org>
CC:	Sebastian Andrzej Siewior <bigeasy@...utronix.de>,
	linux-kernel@...r.kernel.org,
	"Rafael J. Wysocki" <rafael.j.wysocki@...el.com>,
	Ingo Molnar <mingo@...hat.com>,
	Peter Zijlstra <peterz@...radead.org>, tglx@...utronix.de
Subject: Re: [RFC 2/2] sched/fair: prefer a CPU in the "lowest" idle state

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
>> --
>> To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
>> the body of a message to majordomo@...r.kernel.org
>> More majordomo info at  http://vger.kernel.org/majordomo-info.html
>> Please read the FAQ at  http://www.tux.org/lkml/
>>
> 

--
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majordomo@...r.kernel.org
More majordomo info at  http://vger.kernel.org/majordomo-info.html
Please read the FAQ at  http://www.tux.org/lkml/