From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S262359AbTD3TPt (ORCPT ); Wed, 30 Apr 2003 15:15:49 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S262357AbTD3TPt (ORCPT ); Wed, 30 Apr 2003 15:15:49 -0400 Received: from outpost.ds9a.nl ([213.244.168.210]:26802 "EHLO outpost.ds9a.nl") by vger.kernel.org with ESMTP id S262341AbTD3TPs (ORCPT ); Wed, 30 Apr 2003 15:15:48 -0400 Date: Wed, 30 Apr 2003 21:28:09 +0200 From: bert hubert To: P?l Halvorsen Cc: linux-kernel@vger.kernel.org Subject: Re: sendfile Message-ID: <20030430192809.GA8961@outpost.ds9a.nl> Mail-Followup-To: bert hubert , P?l Halvorsen , linux-kernel@vger.kernel.org References: <20030430165103.GA3060@outpost.ds9a.nl> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: User-Agent: Mutt/1.3.28i Sender: linux-kernel-owner@vger.kernel.org X-Mailing-List: linux-kernel@vger.kernel.org On Wed, Apr 30, 2003 at 09:12:17PM +0200, P?l Halvorsen wrote: > It could be useful for applications like streaming video where other > protocols on top provide additional functionality or in a multicast > session where TCP migth not be appropriate. sendfile on UDP would try to send gigabits per second over ppp0... > But should not the 2.4.X kernels have support for chained sk_buffs (like > the BSD mbufs) meaning that support for scatter-gatter I/O from the NIC > should be unneccessary to support zero-copy (i.e., NO in-memory data > copy operations)? No clue what you mean over here. Zero copy means different things to different people. Sendfile eliminates the 'read(to buffer);write(buffer to network);' copy. Some network drivers again may eliminate the 'copy_with_checksum()' step, allowing minus-one-copy, in zerocopy reference frame. Regards, bert -- http://www.PowerDNS.com Open source, database driven DNS Software http://lartc.org Linux Advanced Routing & Traffic Control HOWTO