linux-kernel - Re: [PATCH 09/12] irq: implement IRQ expecting

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Date:	Thu, 17 Jun 2010 17:54:48 +0200
From:	Tejun Heo <tj@...nel.org>
To:	Alan Cox <alan@...rguk.ukuu.org.uk>
CC:	Thomas Gleixner <tglx@...utronix.de>,
	Arjan van de Ven <arjan@...radead.org>, mingo@...e.hu,
	bphilips@...e.de, yinghai@...nel.org, akpm@...ux-foundation.org,
	torvalds@...ux-foundation.org, linux-kernel@...r.kernel.org,
	jeff@...zik.org, linux-ide@...r.kernel.org,
	stern@...land.harvard.edu, gregkh@...e.de, khali@...ux-fr.org
Subject: Re: [PATCH 09/12] irq: implement IRQ expecting

On 06/17/2010 01:43 PM, Alan Cox wrote:
> On Thu, 17 Jun 2010 13:23:27 +0200
> Tejun Heo <tj@...nel.org> wrote:
> 
>> On 06/17/2010 01:12 PM, Thomas Gleixner wrote:
>>>> Hmmm.... oh, I see.  Wouldn't it be much better to use moving avg of
>>>> IRQ durations instead of letting the driver specify it?  Drivers are
>>>> most likely to just hard code it and It's never gonna be accurate.
>>>
>>> Right, but that's probably more accurate than the core code heuristics
>>> ever will be.
>>
>> Eh, not really.  For ATA at least, there will be three different
>> classes of devices.  SSDs, hard drives and optical devices
> 
> At least four: It may also be battery backed RAM.

Yeah, right, there are those crazy devices too but I think they would
fall in a single tick any way.  At any rate, let's say I have those
numbers, how would I feed it into c-state selection?

Thanks.

-- 
tejun

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