Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1762159AbZC1AZ3 (ORCPT ); Fri, 27 Mar 2009 20:25:29 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1754967AbZC1AZO (ORCPT ); Fri, 27 Mar 2009 20:25:14 -0400 Received: from yw-out-2324.google.com ([74.125.46.30]:2969 "EHLO yw-out-2324.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1754289AbZC1AZN convert rfc822-to-8bit (ORCPT ); Fri, 27 Mar 2009 20:25:13 -0400 DomainKey-Signature: a=rsa-sha1; c=nofws; d=gmail.com; s=gamma; h=mime-version:in-reply-to:references:date:message-id:subject:from:to :cc:content-type:content-transfer-encoding; b=cjv74/hQh1saun3D44oe7NO7SzlVzG2kGLJAJ/Wcb8GCDBnnq5QE1iAVCKDmOVcRjj YNbQ2Kq4YWfbx4jTlDh3yfQJlxiQqQOAJAoZ8ZxOhmXLudwKhPvh+ssjAE+yCHypZ6P4 o7i3Zj9pZLLR3pyexMAwtI3PklC78oikoDHHM= MIME-Version: 1.0 In-Reply-To: <49CD6BCC.6080602@garzik.org> References: <1238185471-31152-1-git-send-email-tytso@mit.edu> <1238187031.27455.212.camel@think.oraclecorp.com> <1238187818.27455.217.camel@think.oraclecorp.com> <20090327213052.GC5176@mit.edu> <20090327215454.GH31071@duck.suse.cz> <20090327230902.GG5176@mit.edu> <49CD6BCC.6080602@garzik.org> Date: Fri, 27 Mar 2009 17:24:54 -0700 Message-ID: <72dbd3150903271724n5e7900a5j2486707565cd9d74@mail.gmail.com> Subject: Re: [PATCH 0/3] Ext3 latency improvement patches From: David Rees To: Jeff Garzik Cc: Theodore Tso , Jan Kara , Chris Mason , Ric Wheeler , Linux Kernel Developers List , Ext4 Developers List Content-Type: text/plain; charset=ISO-8859-1 Content-Transfer-Encoding: 8BIT Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 965 Lines: 21 On Fri, Mar 27, 2009 at 5:14 PM, Jeff Garzik wrote: > Theodore Tso wrote: >> OTOH, the really big databases will tend to use direct I/O, so they >> won't be dirtying the page cache anyway. ?So maybe it's not worth the > > Not necessarily... ?From what I understand, a lot of the individual > low-level components in cloud storage, such as GoogleFS's chunk server[1] do > not bypass the page cache, even though they do care about the details of > data caching and data consistency. PostgreSQL does not use direct I/O, either (except for the write-ahead-logs which are written sequentially and only get read during database recovery). I'm sure that most of MySQL's database engines, also don't. -Dave -- 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/