From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S268367AbUHXV6r (ORCPT ); Tue, 24 Aug 2004 17:58:47 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S268365AbUHXV6q (ORCPT ); Tue, 24 Aug 2004 17:58:46 -0400 Received: from viper.oldcity.dca.net ([216.158.38.4]:54952 "HELO viper.oldcity.dca.net") by vger.kernel.org with SMTP id S268367AbUHXV46 (ORCPT ); Tue, 24 Aug 2004 17:56:58 -0400 Subject: Re: [PATCH] Speed up the cdrw packet writing driver From: Lee Revell To: Andrew Morton Cc: Peter Osterlund , axboe@suse.de, linux-kernel In-Reply-To: <20040824144707.100e0cfd.akpm@osdl.org> References: <20040823114329.GI2301@suse.de> <20040824202951.GA24280@suse.de> <20040824144707.100e0cfd.akpm@osdl.org> Content-Type: text/plain Message-Id: <1093384621.817.76.camel@krustophenia.net> Mime-Version: 1.0 X-Mailer: Ximian Evolution 1.4.6 Date: Tue, 24 Aug 2004 17:57:01 -0400 Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org X-Mailing-List: linux-kernel@vger.kernel.org On Tue, 2004-08-24 at 17:47, Andrew Morton wrote: > Peter Osterlund wrote: > > > > Why is it not nice? If the VM has decided to create 400MB of dirty > > data on a DVD+RW packet device, I don't see a problem with submitting > > all bio's at the same time to the packet device. > > We also have a limit on the number of in-flight requests: > /sys/block/sda/queue/nr_requests. It defaults to 128. > > Are you saying that your requests are so huge that each one has 1000 BIOs? > That would be odd, for an IDE interface. > This defaults to 8192 on my (IDE) system. IIRC this value is larger if 48-bit addressing is in use (drive size > ~128GB). It does not seem right to me that the size of your hard drive should dictate the amount of I/O allowed to be in flight. Lee