linux-kernel - Re: [RFC PATCH v3 5/6] sched: pack the idle load balance

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Date:	Tue, 23 Apr 2013 08:30:58 -0700
From:	Arjan van de Ven <arjan@...ux.intel.com>
To:	Alex Shi <alex.shi@...el.com>
CC:	Vincent Guittot <vincent.guittot@...aro.org>,
	Preeti U Murthy <preeti@...ux.vnet.ibm.com>,
	Peter Zijlstra <peterz@...radead.org>,
	linux-kernel <linux-kernel@...r.kernel.org>,
	LAK <linux-arm-kernel@...ts.infradead.org>,
	"linaro-kernel@...ts.linaro.org" <linaro-kernel@...ts.linaro.org>,
	Ingo Molnar <mingo@...nel.org>,
	Russell King - ARM Linux <linux@....linux.org.uk>,
	Paul Turner <pjt@...gle.com>,
	Santosh <santosh.shilimkar@...com>,
	Morten Rasmussen <morten.rasmussen@....com>,
	Chander Kashyap <chander.kashyap@...aro.org>,
	"cmetcalf@...era.com" <cmetcalf@...era.com>,
	"tony.luck@...el.com" <tony.luck@...el.com>,
	Paul McKenney <paulmck@...ux.vnet.ibm.com>,
	Thomas Gleixner <tglx@...utronix.de>,
	Len Brown <len.brown@...el.com>,
	Amit Kucheria <amit.kucheria@...aro.org>,
	Jonathan Corbet <corbet@....net>
Subject: Re: [RFC PATCH v3 5/6] sched: pack the idle load balance

On 4/22/2013 7:23 PM, Alex Shi wrote:
> Thanks you, Preeti and Vincent to talk the power aware scheduler for
> details! believe this open discussion is helpful to conduct a a more
> comprehensive solution. :)
>
>> Hi Preeti,
>>
>> I have had a look at Alex patches but i have some concerns with his patches
>> -There no notion of power domain which is quite important when we speak
>> about power saving IMHO. Packing tasks has got an interest if the idle
>> CPUs can reach a useful low power state independently from busy CPUs.
>> Architectures have different low power state capabilities which must be
>> taken into account. In addition, you can have system which have CPUs
>> with better power efficiency and this kind of system are not taken into
>> account.
>
> I agree with you on this point. and like what's you done to add new flag
> in sched domain.

For x86 we should not be setting such flag then; we don't have a way for some cpu packages to
go to an extra deep power state if they're completely idle.
(this afaik is true for both Intel and AMD)



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