Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1752031Ab0GMFlc (ORCPT ); Tue, 13 Jul 2010 01:41:32 -0400 Received: from fgwmail5.fujitsu.co.jp ([192.51.44.35]:43120 "EHLO fgwmail5.fujitsu.co.jp" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751004Ab0GMFlb convert rfc822-to-8bit (ORCPT ); Tue, 13 Jul 2010 01:41:31 -0400 X-SecurityPolicyCheck-FJ: OK by FujitsuOutboundMailChecker v1.3.1 From: KOSAKI Motohiro To: Minchan Kim Subject: Re: [PATCH v2 2/2] vmscan: shrink_slab() require number of lru_pages, not page order Cc: kosaki.motohiro@jp.fujitsu.com, Christoph Lameter , LKML , linux-mm , Andrew Morton , Mel Gorman , Rik van Riel , Johannes Weiner 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: 8BIT X-Mailer: Becky! ver. 2.50.07 [ja] Date: Tue, 13 Jul 2010 14:41:28 +0900 (JST) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 3045 Lines: 80 > 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 > > With your test result, This patch makes sense to me. > Please, include your test result in description. How's this? ============================================================== >From 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 page order Now, shrink_slab() has following scanning equation. lru_scanned max_pass basic_scan_objects = 4 x ------------- x ----------------------------- lru_pages shrinker->seeks (default:2) scan_objects = 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 = 32, order = 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 gfp_mask, unsigned int order) nr_slab_pages0 = zone_page_state(zone, NR_SLAB_RECLAIMABLE); if (nr_slab_pages0 > zone->min_slab_pages) { + unsigned long lru_pages = 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 gfp_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)) ; -- 1.6.5.2 -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/