From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id ; Fri, 26 Jan 2001 06:37:49 -0500 Received: (majordomo@vger.kernel.org) by vger.kernel.org id ; Fri, 26 Jan 2001 06:37:40 -0500 Received: from zeus.kernel.org ([209.10.41.242]:38109 "EHLO zeus.kernel.org") by vger.kernel.org with ESMTP id ; Fri, 26 Jan 2001 06:37:28 -0500 Date: Fri, 26 Jan 2001 11:35:07 +0000 From: "Stephen C. Tweedie" To: Daniel Phillips Cc: "Stephen C. Tweedie" , linux-kernel@vger.kernel.org Subject: Re: inode->i_dirty_buffers redundant ? Message-ID: <20010126113507.J11607@redhat.com> In-Reply-To: <200101251047.QAA16434@vxindia.veritas.com> <20010125164432.A12984@redhat.com> <3A708722.C21EC12A@innominate.de> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline User-Agent: Mutt/1.2i In-Reply-To: <3A708722.C21EC12A@innominate.de>; from phillips@innominate.de on Thu, Jan 25, 2001 at 09:05:54PM +0100 Sender: linux-kernel-owner@vger.kernel.org X-Mailing-List: linux-kernel@vger.kernel.org Hi, On Thu, Jan 25, 2001 at 09:05:54PM +0100, Daniel Phillips wrote: > "Stephen C. Tweedie" wrote: > > We also maintain the > > per-page buffer lists as caches of the virtual-to-physical mapping to > > avoid redundant bmap()ping. > > Could you clarify that one, please? The buffer contains a physical label for the block's location on disk. The page cache is indexed purely by logical location, so doing IO to/from the page cache requires us to lookup the physical locations of each block within the page. Caching the buffer_heads for page cache pages means that once those lookups are done once, further IO on the same page can bypass the lookup and go straight to disk. --Stephen - To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org Please read the FAQ at http://www.tux.org/lkml/