From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail143.messagelabs.com (mail143.messagelabs.com [216.82.254.35]) by kanga.kvack.org (Postfix) with SMTP id 7B10B6B0208 for ; Thu, 15 Apr 2010 13:27:12 -0400 (EDT) Message-Id: <85DB7083-8E78-4884-9E76-5BD803C530EF@freebsd.org> From: Suleiman Souhlal In-Reply-To: <20100415093214.GV2493@dastard> Content-Type: text/plain; charset=US-ASCII; format=flowed Content-Transfer-Encoding: 7bit Mime-Version: 1.0 (Apple Message framework v936) Subject: Re: [PATCH 1/4] vmscan: delegate pageout io to flusher thread if current is kswapd Date: Thu, 15 Apr 2010 10:27:09 -0700 References: <20100415013436.GO2493@dastard> <20100415130212.D16E.A69D9226@jp.fujitsu.com> <20100415131106.D174.A69D9226@jp.fujitsu.com> <64BE60A8-EEF9-4AC6-AF0A-0ED3CB544726@freebsd.org> <20100415093214.GV2493@dastard> Sender: owner-linux-mm@kvack.org To: Dave Chinner Cc: KOSAKI Motohiro , Mel Gorman , Chris Mason , linux-kernel@vger.kernel.org, linux-mm@kvack.org, linux-fsdevel@vger.kernel.org, suleiman@google.com List-ID: On Apr 15, 2010, at 2:32 AM, Dave Chinner wrote: > On Thu, Apr 15, 2010 at 01:05:57AM -0700, Suleiman Souhlal wrote: >> >> On Apr 14, 2010, at 9:11 PM, KOSAKI Motohiro wrote: >> >>> Now, vmscan pageout() is one of IO throuput degression source. >>> Some IO workload makes very much order-0 allocation and reclaim >>> and pageout's 4K IOs are making annoying lots seeks. >>> >>> At least, kswapd can avoid such pageout() because kswapd don't >>> need to consider OOM-Killer situation. that's no risk. >>> >>> Signed-off-by: KOSAKI Motohiro >> >> What's your opinion on trying to cluster the writes done by pageout, >> instead of not doing any paging out in kswapd? > > XFS already does this in ->writepage to try to minimise the impact > of the way pageout issues IO. It helps, but it is still not as good > as having all the writeback come from the flusher threads because > it's still pretty much random IO. Doesn't the randomness become irrelevant if you can cluster enough pages? > And, FWIW, it doesn't solve the stack usage problems, either. In > fact, it will make them worse as write_one_page() puts another > struct writeback_control on the stack... Sorry, this patch was not meant to solve the stack usage problems. -- Suleiman -- 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