linux-ext4 - Re: page eviction from the buddy cache

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Message-Id: <51874517-8D82-433E-9E10-13167C736D5F@gmail.com>
Date:	Mon, 22 Apr 2013 15:18:59 +0300
From:	Alexey Lyahkov <alexey.lyashkov@...il.com>
To:	Bernd Schubert <bernd.schubert@...tmail.fm>
Cc:	Will Huck <will.huckk@...il.com>, Hugh Dickins <hughd@...gle.com>,
	Theodore Ts'o <tytso@....edu>,
	Andrew Perepechko <anserper@...ru>, linux-ext4@...r.kernel.org,
	akpm@...ux-foundation.org, linux-mm@...ck.org
Subject: Re: page eviction from the buddy cache

Bernd,

I fact marking REQ_META will help with io scheduler().
I and Andrew will discuss it's some time ago, but don't expect a too much performance improvements
anyway - i will pickup patch from Intel jira and ask performance engineer to evaluate it. 

bw. My problem is in memory caching. 
I may rewrite a buddy cache to avoid using a page cache at all as these pages but LRU aging will lost.

On Apr 21, 2013, at 00:18, Bernd Schubert wrote:

> Alex, Andrew,
> 
> did you notice the patch Ted just sent?
> ("ext4: mark all metadata I/O with REQ_META")
> 
> I would like to see a way to mark pages read in with REQ_META to be kept
> in cache preferred over other pages. I guess that would solve LU-15
> (https://jira.hpdd.intel.com/browse/LU-15) and also the direntry-block
> issue I tried to solve about 2 years ago
> (http://patchwork.ozlabs.org/patch/101200/). But using REQ_META to tag
> pages would probably also solve the same issue for other file systems.
> Is there anything already in the mm layer that could be used for that?
> 
> Thanks,
> Bernd
> 

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