linux-kernel - Re: Default zone_reclaim_mode = 1 on NUMA kernel is bad for file/email/web servers

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Message-ID: <20100923114442.GK3952@balbir.in.ibm.com>
Date:	Thu, 23 Sep 2010 17:14:42 +0530
From:	Balbir Singh <balbir@...ux.vnet.ibm.com>
To:	KOSAKI Motohiro <kosaki.motohiro@...fujitsu.com>
Cc:	robm@...tmail.fm, linux-kernel@...r.kernel.org,
	Bron Gondwana <brong@...tmail.fm>,
	linux-mm <linux-mm@...ck.org>,
	Christoph Lameter <cl@...ux-foundation.org>,
	Mel Gorman <mel@....ul.ie>
Subject: Re: Default zone_reclaim_mode = 1 on NUMA kernel is bad for
 file/email/web servers

* KOSAKI Motohiro <kosaki.motohiro@...fujitsu.com> [2010-09-16 19:01:32]:

> +			if (!(zone_reclaim_mode & RECLAIM_CACHE) &&
> +			    (gfp_mask & GFP_MOVABLE_MASK) == GFP_MOVABLE_MASK) {
> +				inc_zone_state(zone, NR_ZONE_CACHE_AVOID);
> +				goto try_next_zone;
> +			}
> +

Interesting approach, so for page cache related applications we expect
RECLAIM_CACHE to be set and hence zone_reclaim to occur. I have
another variation, a new gfp flag called __GFP_FREE_CACHE. You can
find the patches at

http://lwn.net/Articles/391293/
http://article.gmane.org/gmane.linux.kernel.mm/49155

-- 
	Three Cheers,
	Balbir
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