linux-kernel - Re: [PATCHv2 00/16] [FS, MM, block, MMC]: eMMC High Priority Interrupt Feature

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Message-ID: <4FB0BA7B.1050200@kernel.org>
Date:	Mon, 14 May 2012 16:55:39 +0900
From:	Minchan Kim <minchan@...nel.org>
To:	mani <manishrma@...il.com>
CC:	linux-mmc@...r.kernel.org, linux-mm@...ck.org,
	linux-fsdevel@...r.kernel.org, linux-omap@...r.kernel.org,
	linux-kernel@...r.kernel.org
Subject: Re: [PATCHv2 00/16] [FS, MM, block, MMC]: eMMC High Priority Interrupt
 Feature

On 05/14/2012 04:43 PM, mani wrote:

> Dear Kim,
> 
> I have a query here ..
> 
> 
>     My point is that it would be better for read to not preempt
>     write-for-page_reclaim.
>     And we can identify it by PG_reclaim. You can get the idea.
> 
> I think If there is no page available then no read will proceed.

> When read request comes it reclaim the pages (starts the write if

> syncable pages ) and get back after reclaiming the pages.
> Only then a read request will come to the MMC subsystem.

> And i think the reclaim algorithm will reclaim some substantial amount

> of pages at a time instead of a single page.
> So if we get few pages during the reclamation so there will be no
> problem in halting the another write ops for proceeding the reads ?
> 
> Can we think of a scenario when we are reclaiming the pages and write
> ops is going on where as a high priority read for the interrupt handler
> is pending ?
> 
> Please correct me if i am wrong.


For example, System can have lots of order-0 pages but little order-big pages.
In this case, for getting big contiguos memory, reclaimer should write out
dirty pages while it can handle order-0 page read request.


> 
> Thanks & Regards
> Manish



-- 
Kind regards,
Minchan Kim
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