From mboxrd@z Thu Jan 1 00:00:00 1970 Message-ID: <4931721D.7010001@redhat.com> Date: Sat, 29 Nov 2008 11:47:25 -0500 From: Rik van Riel MIME-Version: 1.0 Subject: Re: [PATCH] vmscan: skip freeing memory from zones with lots free References: <20081128060803.73cd59bd@bree.surriel.com> <20081128231933.8daef193.akpm@linux-foundation.org> In-Reply-To: <20081128231933.8daef193.akpm@linux-foundation.org> Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: 7bit Sender: owner-linux-mm@kvack.org Return-Path: To: Andrew Morton Cc: linux-mm@kvack.org, linux-kernel@vger.kernel.org, KOSAKI Motohiro List-ID: Andrew Morton wrote: >> Index: linux-2.6.28-rc5/mm/vmscan.c >> =================================================================== >> --- linux-2.6.28-rc5.orig/mm/vmscan.c 2008-11-28 05:53:56.000000000 -0500 >> +++ linux-2.6.28-rc5/mm/vmscan.c 2008-11-28 06:05:29.000000000 -0500 >> @@ -1510,6 +1510,9 @@ static unsigned long shrink_zones(int pr >> if (zone_is_all_unreclaimable(zone) && >> priority != DEF_PRIORITY) >> continue; /* Let kswapd poll it */ >> + if (zone_watermark_ok(zone, sc->order, >> + 4*zone->pages_high, high_zoneidx, 0)) >> + continue; /* Lots free already */ >> sc->all_unreclaimable = 0; >> } else { >> /* > > We already tried this, or something very similar in effect, I think... Yes, we have a check just like this in balance_pgdat(). It's been there forever with no ill effect. > commit 26e4931632352e3c95a61edac22d12ebb72038fe > Author: akpm > Date: Sun Sep 8 19:21:55 2002 +0000 > > [PATCH] refill the inactive list more quickly > > Fix a problem noticed by Ed Tomlinson: under shifting workloads the > shrink_zone() logic will refill the inactive load too slowly. > > Bale out of the zone scan when we've reclaimed enough pages. Fixes a > rarely-occurring problem wherein refill_inactive_zone() ends up > shuffling 100,000 pages and generally goes silly. This is not a bale out, this is a "skip zones that have way too many free pages already". Kswapd has been doing this for years already. -- All rights reversed. -- To unsubscribe, send a message with 'unsubscribe linux-mm' in the body to majordomo@kvack.org. For more info on Linux MM, see: http://www.linux-mm.org/ . Don't email: email@kvack.org