From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S964961AbVLFMRX (ORCPT ); Tue, 6 Dec 2005 07:17:23 -0500 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S964975AbVLFMRJ (ORCPT ); Tue, 6 Dec 2005 07:17:09 -0500 Received: from souterrain.chygwyn.com ([194.39.143.233]:52097 "EHLO souterrain.chygwyn.com") by vger.kernel.org with ESMTP id S964961AbVLFMQq (ORCPT ); Tue, 6 Dec 2005 07:16:46 -0500 Date: Tue, 6 Dec 2005 12:28:57 +0000 From: Steven Whitehouse To: kernel coder Cc: linux-kernel@vger.kernel.org Subject: Re: zero copy Message-ID: <20051206122857.GA11688@souterrain.chygwyn.com> References: Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: User-Agent: Mutt/1.4.1i Organization: ChyGwyn Limited Sender: linux-kernel-owner@vger.kernel.org X-Mailing-List: linux-kernel@vger.kernel.org Hi, See sock_no_sendpage() in linux/net/core/sock.c for when network protocols don't support zerocopy and tcp_sendpage() in linux/net/ipv4/tcp.c for an example where it is supported. The NETIF_F_SG and TCP_ZC_CSUM_FLAGS test in the latter function is probably what you are after? Steve. On Tue, Dec 06, 2005 at 04:09:30AM -0800, kernel coder wrote: > hi, > i'm trying to track the code flow of sendfile system call.Mine > ethernet card doesn't have scatter gather and checksum calculation > features.So stack should be making a copy of data. > > Please tell me where in sendfile code flow,check for scatter gather > and cecksum features is made so that stack can decide whether to copy > data from user space or not. > > lhrkernelcoder > - > To unsubscribe from this list: send the line "unsubscribe linux-kernel" in > the body of a message to majordomo@vger.kernel.org > More majordomo info at http://vger.kernel.org/majordomo-info.html > Please read the FAQ at http://www.tux.org/lkml/