From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S261682AbTDFNVW (for ); Sun, 6 Apr 2003 09:21:22 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S261693AbTDFNVW (for ); Sun, 6 Apr 2003 09:21:22 -0400 Received: from ns.virtualhost.dk ([195.184.98.160]:63469 "EHLO virtualhost.dk") by vger.kernel.org with ESMTP id S261682AbTDFNVV (for ); Sun, 6 Apr 2003 09:21:21 -0400 Date: Sun, 6 Apr 2003 15:32:50 +0200 From: Jens Axboe To: John Bradford Cc: alan@lxorguk.ukuu.org.uk, linux-kernel@vger.kernel.org Subject: Re: [PATCH] take 48-bit lba a bit further Message-ID: <20030406133250.GN786@suse.de> References: <20030406130737.GL786@suse.de> <200304061332.h36DWnaD000165@81-2-122-30.bradfords.org.uk> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <200304061332.h36DWnaD000165@81-2-122-30.bradfords.org.uk> Sender: linux-kernel-owner@vger.kernel.org X-Mailing-List: linux-kernel@vger.kernel.org On Sun, Apr 06 2003, John Bradford wrote: > > Thanks for taking the previous bit Alan, here's an incremental update to > > 2.5.66-ac2. Just cleans up the 'when to use 48-bit lba' logic a bit per > > Andries suggestion, and also expands the request size for 48-bit lba > > capable drives to 512KiB. > > > > Works perfectly in testing here, ext2/3 generates nice big 512KiB > > requests and the drive flies. > > Then, don't we want to be using 48-bit lba all the time on compatible devices > instead of falling back to 28-bit when possible to save a small amount of > instruction overhead? (Or is that what we're doing already? I haven't really > had the time to follow this thread). The logic in the patch is to enable large requests _if_ the drive can do 48-bit lba. However, we will only use 48-bit lba commands if the request is either beyond 2^28 sectors _or_ bigger than 256 sectors since neither of these can be addressed with 28-bit lba. See rq_lba48 in the patch, it explains it. -- Jens Axboe