linux-kernel - Re: [linux-pm] [PATCH 0/8] Suspend block api (version 8)

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Message-ID: <20100527171553.GC9625@nokia.com>
Date:	Thu, 27 May 2010 20:15:53 +0300
From:	Felipe Balbi <felipe.balbi@...ia.com>
To:	ext Alan Stern <stern@...land.harvard.edu>
Cc:	"Balbi Felipe (Nokia-D/Helsinki)" <felipe.balbi@...ia.com>,
	Thomas Gleixner <tglx@...utronix.de>,
	Arve Hjønnevåg <arve@...roid.com>,
	Peter Zijlstra <peterz@...radead.org>,
	"Paul@...p1.linux-foundation.org" <Paul@...p1.linux-foundation.org>,
	LKML <linux-kernel@...r.kernel.org>,
	Florian Mickler <florian@...kler.org>,
	Linux OMAP Mailing List <linux-omap@...r.kernel.org>,
	Linux PM <linux-pm@...ts.linux-foundation.org>,
	Alan Cox <alan@...rguk.ukuu.org.uk>
Subject: Re: [linux-pm] [PATCH 0/8] Suspend block api (version 8)

On Thu, May 27, 2010 at 07:04:24PM +0200, ext Alan Stern wrote:
>On Thu, 27 May 2010, Felipe Balbi wrote:
>
>> On Thu, May 27, 2010 at 05:06:23PM +0200, ext Alan Stern wrote:
>> >If people don't mind, here is a greatly simplified summary of the
>> >comments and objections I have seen so far on this thread:
>> >
>> >	The in-kernel suspend blocker implementation is okay, even
>> >	beneficial.
>>
>> I disagree here. I believe expressing that as QoS is much better. Let
>> the kernel decide which power state is better as long as I can say I
>> need 100us IRQ latency or 100ms wakeup latency.
>
>Does this mean you believe "echo mem >/sys/power/state" is bad and
>should be removed?  Or "echo disk >/sys/power/state"?  They pay no
>attention to latencies or other requirements.

no, not at all. I think they are also really useful. But I also think 
in-kernel suspend blockers are unnecessary. I think runtime pm + cpuidle 
+ cpufreq is well enough for all cases. We just need to give those three 
information about desired latencies.

-- 
balbi

DefectiveByDesign.org
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