From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail202.messagelabs.com (mail202.messagelabs.com [216.82.254.227]) by kanga.kvack.org (Postfix) with SMTP id 1FC806B02A3 for ; Tue, 13 Jul 2010 01:41:32 -0400 (EDT) Received: from m4.gw.fujitsu.co.jp ([10.0.50.74]) by fgwmail5.fujitsu.co.jp (Fujitsu Gateway) with ESMTP id o6D5fTIX008071 for (envelope-from kosaki.motohiro@jp.fujitsu.com); Tue, 13 Jul 2010 14:41:29 +0900 Received: from smail (m4 [127.0.0.1]) by outgoing.m4.gw.fujitsu.co.jp (Postfix) with ESMTP id 8B65445DE6E for ; Tue, 13 Jul 2010 14:41:29 +0900 (JST) Received: from s4.gw.fujitsu.co.jp (s4.gw.fujitsu.co.jp [10.0.50.94]) by m4.gw.fujitsu.co.jp (Postfix) with ESMTP id 51D9345DE60 for ; Tue, 13 Jul 2010 14:41:29 +0900 (JST) Received: from s4.gw.fujitsu.co.jp (localhost.localdomain [127.0.0.1]) by s4.gw.fujitsu.co.jp (Postfix) with ESMTP id 35FCF1DB803E for ; Tue, 13 Jul 2010 14:41:29 +0900 (JST) Received: from ml14.s.css.fujitsu.com (ml14.s.css.fujitsu.com [10.249.87.104]) by s4.gw.fujitsu.co.jp (Postfix) with ESMTP id D36DF1DB803A for ; Tue, 13 Jul 2010 14:41:28 +0900 (JST) From: KOSAKI Motohiro Subject: Re: [PATCH v2 2/2] vmscan: shrink_slab() require number of lru_pages, not page order In-Reply-To: References: <20100708163934.CD37.A69D9226@jp.fujitsu.com> Message-Id: <20100713144008.EA52.A69D9226@jp.fujitsu.com> MIME-Version: 1.0 Content-Type: text/plain; charset="UTF-8" Content-Transfer-Encoding: quoted-printable Date: Tue, 13 Jul 2010 14:41:28 +0900 (JST) Sender: owner-linux-mm@kvack.org To: Minchan Kim Cc: kosaki.motohiro@jp.fujitsu.com, Christoph Lameter , LKML , linux-mm , Andrew Morton , Mel Gorman , Rik van Riel , Johannes Weiner List-ID: > On Thu, Jul 8, 2010 at 4:40 PM, KOSAKI Motohiro > wrote: > > Fix simple argument error. Usually 'order' is very small value than > > lru_pages. then it can makes unnecessary icache dropping. > > > > Signed-off-by: KOSAKI Motohiro > Reviewed-by: Minchan Kim >=20 > With your test result, This patch makes sense to me. > Please, include your test result in description. How's this? =3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D= =3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D= =3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D =46rom 19872d74875e2331cbe7eca46c8ef65f5f00d7c4 Mon Sep 17 00:00:00 2001 From: KOSAKI Motohiro Date: Tue, 13 Jul 2010 13:39:11 +0900 Subject: [PATCH] vmscan: shrink_slab() require number of lru_pages, not pag= e order Now, shrink_slab() has following scanning equation. lru_scanned max_pass basic_scan_objects =3D 4 x ------------- x ----------------------------- lru_pages shrinker->seeks (default:2) scan_objects =3D min(basic_scan_objects, max_pass * 2) Then, If we pass very small value as lru_pages instead real number of lru pages, shrink_slab() drop much objects rather than necessary. and now, __zone_reclaim() pass 'order' as lru_pages by mistake. that makes bad result. Example, If we receive very low memory pressure (scan =3D 32, order =3D 0), shrink_slab() via zone_reclaim() always drop _all_ icache/dcache objects. (see above equation, very small lru_pages make very big scan_objects result) This patch fixes it. Signed-off-by: KOSAKI Motohiro Reviewed-by: Minchan Kim Acked-by: Christoph Lameter Acked-by: Rik van Riel --- mm/vmscan.c | 4 +++- 1 files changed, 3 insertions(+), 1 deletions(-) diff --git a/mm/vmscan.c b/mm/vmscan.c index 6ff51c0..1bf9f72 100644 --- a/mm/vmscan.c +++ b/mm/vmscan.c @@ -2612,6 +2612,8 @@ static int __zone_reclaim(struct zone *zone, gfp_t gf= p_mask, unsigned int order) =20 nr_slab_pages0 =3D zone_page_state(zone, NR_SLAB_RECLAIMABLE); if (nr_slab_pages0 > zone->min_slab_pages) { + unsigned long lru_pages =3D zone_reclaimable_pages(zone); + /* * shrink_slab() does not currently allow us to determine how * many pages were freed in this zone. So we take the current @@ -2622,7 +2624,7 @@ static int __zone_reclaim(struct zone *zone, gfp_t gf= p_mask, unsigned int order) * Note that shrink_slab will free memory on all zones and may * take a long time. */ - while (shrink_slab(sc.nr_scanned, gfp_mask, order) && + while (shrink_slab(sc.nr_scanned, gfp_mask, lru_pages) && (zone_page_state(zone, NR_SLAB_RECLAIMABLE) + nr_pages > nr_slab_pages0)) ; --=20 1.6.5.2 -- 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