Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S966110AbXJQAAn (ORCPT ); Tue, 16 Oct 2007 20:00:43 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S965515AbXJQAAI (ORCPT ); Tue, 16 Oct 2007 20:00:08 -0400 Received: from static-71-162-243-5.phlapa.fios.verizon.net ([71.162.243.5]:56981 "EHLO grelber.thyrsus.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S965459AbXJQAAF (ORCPT ); Tue, 16 Oct 2007 20:00:05 -0400 From: Rob Landley Organization: Boundaries Unlimited To: Alan Cox Subject: Re: OOM killer gripe (was Re: What still uses the block layer?) Date: Tue, 16 Oct 2007 18:59:54 -0500 User-Agent: KMail/1.9.6 Cc: "Eric W. Biederman" , Nick Piggin , Theodore Tso , James Bottomley , Matthew Wilcox , linux-kernel@vger.kernel.org, linux-scsi@vger.kernel.org, Suparna Bhattacharya , Nick Piggin References: <200710112011.22000.rob@landley.net> <200710160138.57893.rob@landley.net> <20071016112859.1b0fba0e@the-village.bc.nu> In-Reply-To: <20071016112859.1b0fba0e@the-village.bc.nu> MIME-Version: 1.0 Content-Type: text/plain; charset="iso-8859-1" Content-Transfer-Encoding: 7bit Content-Disposition: inline Message-Id: <200710161859.55325.rob@landley.net> Sender: linux-kernel-owner@vger.kernel.org X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 1469 Lines: 42 On Tuesday 16 October 2007 5:28:59 am Alan Cox wrote: > > I'm sure somebody will eventually write an OLS paper or something on the > > advisability of making swapping decisions with 4k granularity when disks > > really want bigger I/O transactions. > > Funnily enough someone thought of that many years ago. They even added > and documented it, then they made it adjustable. > > See the vm section of Documentation/filesystems/proc.txt I presume you refer to: page-cluster ------------ page-cluster controls the number of pages which are written to swap in a single attempt. The swap I/O size. It is a logarithmic value - setting it to zero means "1 page", setting it to 1 means "2 pages", setting it to 2 means "4 pages", etc. The default value is three (eight pages at a time). There may be some small benefits in tuning this to a different value if your workload is swap-intensive. I didn't know that controlled whether the pages were contiguous (or written to contiguous locations in swap). I thought it was just how many the VM tried to free at a time. Still, worth a tweak. Thanks. > Alan Rob -- "One of my most productive days was throwing away 1000 lines of code." - Ken Thompson. - 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/