From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1750963AbWDTTsn (ORCPT ); Thu, 20 Apr 2006 15:48:43 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1751169AbWDTTsn (ORCPT ); Thu, 20 Apr 2006 15:48:43 -0400 Received: from ns.virtualhost.dk ([195.184.98.160]:50758 "EHLO virtualhost.dk") by vger.kernel.org with ESMTP id S1750963AbWDTTsn (ORCPT ); Thu, 20 Apr 2006 15:48:43 -0400 Date: Thu, 20 Apr 2006 21:49:14 +0200 From: Jens Axboe To: Linh Dang Cc: linux-kernel@vger.kernel.org Subject: Re: Linux 2.6.17-rc2 Message-ID: <20060420194914.GL4717@suse.de> References: <20060419200001.fe2385f4.diegocg@gmail.com> <20060420145041.GE4717@suse.de> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: Sender: linux-kernel-owner@vger.kernel.org X-Mailing-List: linux-kernel@vger.kernel.org On Thu, Apr 20 2006, Linh Dang wrote: > Jens Axboe wrote: > > > On Wed, Apr 19 2006, Linus Torvalds wrote: > >> There are some other buffer management system calls that I haven't > >> done yet (and when I say "I haven't done yet", I obviously mean > >> "that I hope some other sucker will do for me, since I'm lazy"), > >> but that are obvious future extensions: > > > > Well it's worked so far, hasn't it? :-) > > > >> - an ioctl/fcntl to set the maximum size of the buffer. Right now > >> it's > >> hardcoded to 16 "buffer entries" (which in turn are normally limited to > >> one page each, although there's nothing that _requires_ that a buffer > >> entry always be a page). > > > > This is on a TODO, but not very high up since I've yet to see a case > > where the current 16 page limitation is an issue. I'm sure something > > will come up eventually, but until then I'd rather not bother. > > DVD burning! splicing those huge VOB files into the dvd device would > be nice. And believe me, the current 16 entries of the pipe is nowhere > enough to sustain burning at 8X avg speed or higher. > > It's a special case but it'd benefit a LOT of ppl ;-) (don't drop the cc list) DVD burning probably isn't a good splice fit, since you need to do more than actually just point the device at the data. SG_IO is already zero-copy as it maps the user data into the kernel without copying, so there's very little room for improvement there to begin with. -- Jens Axboe