From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail172.messagelabs.com (mail172.messagelabs.com [216.82.254.3]) by kanga.kvack.org (Postfix) with ESMTP id F1B1B6B0246 for ; Tue, 6 Jul 2010 21:15:42 -0400 (EDT) Date: Tue, 6 Jul 2010 21:15:33 -0400 From: Christoph Hellwig Subject: Re: [PATCH 12/14] vmscan: Do not writeback pages in direct reclaim Message-ID: <20100707011533.GB3630@infradead.org> References: <20100702125155.69c02f85.akpm@linux-foundation.org> <20100705134949.GC13780@csn.ul.ie> <20100706093529.CCD1.A69D9226@jp.fujitsu.com> <20100706101235.GE13780@csn.ul.ie> <20100706152539.GG13780@csn.ul.ie> <20100706202758.GC18210@cmpxchg.org> <20100707002458.GI13780@csn.ul.ie> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20100707002458.GI13780@csn.ul.ie> Sender: owner-linux-mm@kvack.org To: Mel Gorman Cc: Minchan Kim , Johannes Weiner , KOSAKI Motohiro , Andrew Morton , linux-kernel@vger.kernel.org, linux-fsdevel@vger.kernel.org, linux-mm@kvack.org, Dave Chinner , Chris Mason , Nick Piggin , Rik van Riel , Christoph Hellwig , KAMEZAWA Hiroyuki , Andrea Arcangeli List-ID: On Wed, Jul 07, 2010 at 01:24:58AM +0100, Mel Gorman wrote: > What I have now is direct writeback for anon files. For files be it from > kswapd or direct reclaim, I kick writeback pre-emptively by an amount based > on the dirty pages encountered because monitoring from systemtap indicated > that we were getting a large percentage of the dirty file pages at the end > of the LRU lists (bad). Initial tests show that page reclaim writeback is > reduced from kswapd by 97% with this sort of pre-emptive kicking of flusher > threads based on these figures from sysbench. That sounds like yet another bad aid to me. Instead it would be much better to not have so many file pages at the end of LRU by tuning the flusher threads and VM better. -- 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