From mboxrd@z Thu Jan 1 00:00:00 1970 From: KOSAKI Motohiro Subject: [PATCH] vmscan: synchronous lumpy reclaim don't call congestion_wait() Date: Sun, 1 Aug 2010 18:12:47 +0900 (JST) Message-ID: <20100801180751.4B0E.A69D9226@jp.fujitsu.com> References: <20100801085134.GA15577@localhost> Mime-Version: 1.0 Content-Type: text/plain; charset="US-ASCII" Content-Transfer-Encoding: quoted-printable 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 To: Wu Fengguang Return-path: In-Reply-To: <20100801085134.GA15577@localhost> Sender: owner-linux-mm@kvack.org List-Id: linux-fsdevel.vger.kernel.org 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