Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S964988AbXBLSRI (ORCPT ); Mon, 12 Feb 2007 13:17:08 -0500 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S964971AbXBLSRI (ORCPT ); Mon, 12 Feb 2007 13:17:08 -0500 Received: from nf-out-0910.google.com ([64.233.182.184]:32320 "EHLO nf-out-0910.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S964988AbXBLSRH (ORCPT ); Mon, 12 Feb 2007 13:17:07 -0500 DomainKey-Signature: a=rsa-sha1; c=nofws; d=gmail.com; s=beta; h=received:message-id:date:from:reply-to:to:subject:cc:in-reply-to:mime-version:content-type:content-transfer-encoding:content-disposition:references; b=c1jj/kD4xyNQoWxmDIftyPtG+cunPI3QXnn2xPAK1GtBBW+zPOnNoEtUhN3tL3kzlAZWaQLAZyih8pSHvaNG96hsu1lkTkeVfqQulNtFYyMxkduXcxaZnS7p0ijv2kF9INrKesoe952RcCCQhBH6z2jmN/q4fjpGGhVmHI1LN9M= Message-ID: <2c0942db0702121017i3ab273b0qf9f31654f73519ba@mail.gmail.com> Date: Mon, 12 Feb 2007 10:17:03 -0800 From: "Ray Lee" Reply-To: ray-gmail@madrabbit.org To: "Martin A. Fink" Subject: Re: SATA-performance: Linux vs. FreeBSD Cc: "Andi Kleen" , linux-kernel@vger.kernel.org In-Reply-To: <200702121856.29729.fink@mpe.mpg.de> MIME-Version: 1.0 Content-Type: text/plain; charset=ISO-8859-1; format=flowed Content-Transfer-Encoding: 7bit Content-Disposition: inline References: <200702121502.17130.fink@mpe.mpg.de> <200702121727.17108.fink@mpe.mpg.de> <200702121856.29729.fink@mpe.mpg.de> Sender: linux-kernel-owner@vger.kernel.org X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 1479 Lines: 33 On 2/12/07, Martin A. Fink wrote: > Am Montag, 12. Februar 2007 19:41 schrieben Sie: > I have to store big amounts of data coming from 2 digital cameras to disk. > Thus I have to write blocks of around 1 MB at 30 to 50 frames per second for > a long period of time. So it is important for me that the harddisk drive is > reliable in the sense of "if it is capable of 50 MB/s then it should operate > at this speed. Constantly." Ah, here is a misunderstanding, I think. By default, Linux won't start writing out dirty buffers until something like 40% of memory is used. This is to help common workloads where many temporary files are created and destroyed, or even data that gets written then overwritten shortly after. If the kernel were to immediately write out that dirty data, it would be slower than leaving it in memory for those workloads. But since that isn't best for everyone, there's a parameter that controls that dirty threshold. Setting that to a lower value will help even out the writeout, and start it early, just as you seem to be requesting. Hmm, it may be one of: /proc/sys/vm/dirty_ratio /proc/sys/vm/dirty_background_ratio Try tweaking those to much lower values and see if that helps. Ray - 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/