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Date: Mon, 28 Dec 2009 09:27:38 +0530 From: Balbir Singh <balbir@...ux.vnet.ibm.com> To: Rik van Riel <riel@...hat.com> Cc: Minchan Kim <minchan.kim@...il.com>, Andrew Morton <akpm@...ux-foundation.org>, lkml <linux-kernel@...r.kernel.org>, linux-mm <linux-mm@...ck.org>, Hugh Dickins <hugh.dickins@...cali.co.uk>, KOSAKI Motohiro <kosaki.motohiro@...fujitsu.com> Subject: Re: [PATCH -mmotm-2009-12-10-17-19] Prevent churning of zero page in LRU list. * Balbir Singh <balbir@...ux.vnet.ibm.com> [2009-12-28 09:26:39]: > * Rik van Riel <riel@...hat.com> [2009-12-27 22:22:20]: > > > On 12/27/2009 09:53 PM, Minchan Kim wrote: > > > > > >VM doesn't add zero page to LRU list. > > >It means zero page's churning in LRU list is pointless. > > > > > >As a matter of fact, zero page can't be promoted by mark_page_accessed > > >since it doesn't have PG_lru. > > > > > >This patch prevent unecessary mark_page_accessed call of zero page > > >alghouth caller want FOLL_TOUCH. > > > > > >Signed-off-by: Minchan Kim<minchan.kim@...il.com> > > > > The code looks correct, but I wonder how frequently we run into > > the zero page in this code, vs. how much the added cost is of > > having this extra code in follow_page. > > > > What kind of problem were you running into that motivated you > > to write this patch? > > > > Frequent moving of zero page should ideally put it to the head of the > LRU list, leaving it untouched is likely to cause it to be scanned > often - no? Should this be moved to the unevictable list? > Sorry, I replied to wrong email, I should have been clearer that this question is for Minchan Kim. -- Balbir -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@...r.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
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