linux-kernel - Re: [patch 00/20] VM pageout scalability improvements

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Message-ID: <476D7334.4010301@linux.vnet.ibm.com>
Date:	Sun, 23 Dec 2007 01:57:32 +0530
From:	Balbir Singh <balbir@...ux.vnet.ibm.com>
To:	Rik van Riel <riel@...hat.com>
CC:	linux-mm@...ck.org, linux-kernel@...r.kernel.org,
	lee.shermerhorn@...com
Subject: Re: [patch 00/20] VM pageout scalability improvements

Rik van Riel wrote:
> On large memory systems, the VM can spend way too much time scanning
> through pages that it cannot (or should not) evict from memory. Not
> only does it use up CPU time, but it also provokes lock contention
> and can leave large systems under memory presure in a catatonic state.
> 

Hi, Rik,

I remember you mentioning that by large memory systems you mean systems
with at-least 128GB, does this definition still hold?

> This patch series improves VM scalability by:
> 
> 1) making the locking a little more scalable
> 
> 2) putting filesystem backed, swap backed and non-reclaimable pages
>    onto their own LRUs, so the system only scans the pages that it
>    can/should evict from memory
> 
> 3) switching to SEQ replacement for the anonymous LRUs, so the
>    number of pages that need to be scanned when the system
>    starts swapping is bound to a reasonable number
> 
> The noreclaim patches come verbatim from Lee Schermerhorn and
> Nick Piggin.  I have not taken a detailed look at them yet and
> all I have done is fix the rejects against the latest -mm kernel.
> 

Is there a consolidate patch available, it makes it easier to test.

> I am posting this series now because I would like to get more
> feedback, while I am studying and improving the noreclaim patches
> myself.
> 

What kind of tests show the problem? I'll try and review and test the code.

-- 
	Warm Regards,
	Balbir Singh
	Linux Technology Center
	IBM, ISTL
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