Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id ; Mon, 7 Oct 2002 16:22:20 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id ; Mon, 7 Oct 2002 16:22:20 -0400 Received: from dsl-213-023-021-129.arcor-ip.net ([213.23.21.129]:7852 "EHLO starship") by vger.kernel.org with ESMTP id ; Mon, 7 Oct 2002 16:22:19 -0400 Content-Type: text/plain; charset=US-ASCII From: Daniel Phillips To: Andrew Morton Subject: Re: The reason to call it 3.0 is the desktop (was Re: [OT] 2.6 not 3.0 - (NUMA)) Date: Mon, 7 Oct 2002 22:22:51 +0200 X-Mailer: KMail [version 1.3.2] Cc: Linus Torvalds , "Martin J. Bligh" , Oliver Neukum , Rob Landley , linux-kernel@vger.kernel.org References:

<3DA1EB1F.C992353@digeo.com> In-Reply-To: <3DA1EB1F.C992353@digeo.com> MIME-Version: 1.0 Content-Transfer-Encoding: 7BIT Message-Id: Sender: linux-kernel-owner@vger.kernel.org X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 989 Lines: 24 On Monday 07 October 2002 22:14, Andrew Morton wrote: > Daniel Phillips wrote: > > > > This is easy to verify: say you have 100 MB of kernel source stored in, say, > > 50 different clumps on disk. > > Disks use segmentation on their readahead buffers. Typically four-way. > So they will only buffer four different chunks of disk at a time. > > If you're reading from 50 different places on disk, the disk keeps > invalidating readahead at the segment level. Sure, and kernel-based physical readahead would not have that problem. (Kernel-based physical readahead has its own problems, for example: how do you determine that a given physical block is already cached in an inode and so should be ignored as a readahead candidate?) -- Daniel - 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/