Re: [PATCH] vmscan: skip freeing memory from zones with lots free
From: Rik van Riel
Date: Sat Nov 29 2008 - 11:47:44 EST
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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