Messages in this thread | | | Date | Sat, 29 Nov 2008 11:47:25 -0500 | From | Rik van Riel <> | Subject | Re: [PATCH] vmscan: skip freeing memory from zones with lots free |
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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 <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.
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