Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S262727AbVAFFGH (ORCPT ); Thu, 6 Jan 2005 00:06:07 -0500 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S262728AbVAFFGH (ORCPT ); Thu, 6 Jan 2005 00:06:07 -0500 Received: from fw.osdl.org ([65.172.181.6]:47515 "EHLO mail.osdl.org") by vger.kernel.org with ESMTP id S262727AbVAFFGE (ORCPT ); Thu, 6 Jan 2005 00:06:04 -0500 Date: Wed, 5 Jan 2005 21:05:39 -0800 From: Andrew Morton To: Andrea Arcangeli Cc: nickpiggin@yahoo.com.au, riel@redhat.com, marcelo.tosatti@cyclades.com, linux-kernel@vger.kernel.org Subject: Re: [PATCH][5/?] count writeback pages in nr_scanned Message-Id: <20050105210539.19807337.akpm@osdl.org> In-Reply-To: <20050106045932.GN4597@dualathlon.random> References: <20050105134457.03aca488.akpm@osdl.org> <20050105203217.GB17265@logos.cnet> <41DC7D86.8050609@yahoo.com.au> <20050105173624.5c3189b9.akpm@osdl.org> <41DCB577.9000205@yahoo.com.au> <20050105202611.65eb82cf.akpm@osdl.org> <41DCC014.80007@yahoo.com.au> <20050105204706.0781d672.akpm@osdl.org> <20050106045932.GN4597@dualathlon.random> X-Mailer: Sylpheed version 0.9.7 (GTK+ 1.2.10; i386-redhat-linux-gnu) Mime-Version: 1.0 Content-Type: text/plain; charset=US-ASCII Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 732 Lines: 16 Andrea Arcangeli wrote: > > The fix is very simple and it is to call wait_on_page_writeback on one > of the pages under writeback. eek, no. That was causing waits of five seconds or more. Fixing this caused the single greatest improvement in page allocator latency in early 2.5. We're totally at the mercy of the elevator algorithm this way. If we're to improve things in there we want to wait on _any_ eligible page becoming reclaimable, not on a particular page. - 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/