From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail203.messagelabs.com (mail203.messagelabs.com [216.82.254.243]) by kanga.kvack.org (Postfix) with SMTP id 9BCF16B02BD for ; Sun, 1 Aug 2010 05:12:52 -0400 (EDT) Received: from m4.gw.fujitsu.co.jp ([10.0.50.74]) by fgwmail7.fujitsu.co.jp (Fujitsu Gateway) with ESMTP id o719Cn0A024581 for (envelope-from kosaki.motohiro@jp.fujitsu.com); Sun, 1 Aug 2010 18:12:50 +0900 Received: from smail (m4 [127.0.0.1]) by outgoing.m4.gw.fujitsu.co.jp (Postfix) with ESMTP id 9280645DE79 for ; Sun, 1 Aug 2010 18:12:49 +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 6498E45DE60 for ; Sun, 1 Aug 2010 18:12:49 +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 3DA4C1DB803F for ; Sun, 1 Aug 2010 18:12:49 +0900 (JST) Received: from m105.s.css.fujitsu.com (m105.s.css.fujitsu.com [10.249.87.105]) by s4.gw.fujitsu.co.jp (Postfix) with ESMTP id E9F5A1DB803A for ; Sun, 1 Aug 2010 18:12:48 +0900 (JST) From: KOSAKI Motohiro Subject: [PATCH] vmscan: synchronous lumpy reclaim don't call congestion_wait() In-Reply-To: <20100801085134.GA15577@localhost> References: <20100801085134.GA15577@localhost> Message-Id: <20100801180751.4B0E.A69D9226@jp.fujitsu.com> MIME-Version: 1.0 Content-Type: text/plain; charset="US-ASCII" Content-Transfer-Encoding: quoted-printable Date: Sun, 1 Aug 2010 18:12:47 +0900 (JST) Sender: owner-linux-mm@kvack.org To: Wu Fengguang Cc: kosaki.motohiro@jp.fujitsu.com, Andrew Morton , Mel Gorman , Minchan Kim , Andy Whitcroft , Rik van Riel , Christoph Hellwig , "linux-kernel@vger.kernel.org" , "linux-fsdevel@vger.kernel.org" , "linux-mm@kvack.org" , Dave Chinner , Chris Mason , Nick Piggin , Johannes Weiner , KAMEZAWA Hiroyuki , Andrea Arcangeli , Andreas Mohr , Bill Davidsen , Ben Gamari List-ID: rebased onto Wu's patch ---------------------------------------------- =46rom 35772ad03e202c1c9a2252de3a9d3715e30d180f Mon Sep 17 00:00:00 2001 From: KOSAKI Motohiro Date: Sun, 1 Aug 2010 17:23:41 +0900 Subject: [PATCH] vmscan: synchronous lumpy reclaim don't call congestion_wa= it() congestion_wait() mean "waiting for number of requests in IO queue is under congestion threshold". That said, if the system have plenty dirty pages, flusher thread push new request to IO queue conteniously. So, IO queue are not cleared congestion status for a long time. thus, congestion_wait(HZ/10) is almostly equivalent schedule_timeout(HZ/10). If the system 512MB memory, DEF_PRIORITY mean 128kB scan and It takes 4096 shrink_page_list() calls to scan 128kB (i.e. 128kB/32=3D4096) memory. 4096 times 0.1sec stall makes crazy insane long stall. That shouldn't. In the other hand, this synchronous lumpy reclaim donesn't need this congestion_wait() at all. shrink_page_list(PAGEOUT_IO_SYNC) cause to call wait_on_page_writeback() and it provide sufficient waiting. Signed-off-by: KOSAKI Motohiro Reviewed-by: Wu Fengguang --- mm/vmscan.c | 2 -- 1 files changed, 0 insertions(+), 2 deletions(-) diff --git a/mm/vmscan.c b/mm/vmscan.c index 972c8f0..c5e673e 100644 --- a/mm/vmscan.c +++ b/mm/vmscan.c @@ -1339,8 +1339,6 @@ shrink_inactive_list(unsigned long nr_to_scan, struct= zone *zone, =20 /* Check if we should syncronously wait for writeback */ if (should_reclaim_stall(nr_taken, nr_reclaimed, priority, sc)) { - congestion_wait(BLK_RW_ASYNC, HZ/10); - /* * The attempt at page out may have made some * of the pages active, mark them inactive again. --=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