From mboxrd@z Thu Jan 1 00:00:00 1970 From: Evgeniy Polyakov Subject: Re: Packet mmap: TX RING and zero copy Date: Wed, 3 Sep 2008 17:27:34 +0400 Message-ID: <20080903132734.GA17541@2ka.mipt.ru> References: <20080902194603.GA2825@2ka.mipt.ru> <7e0dd21a0809030056q2bfd0344kf3b86a90a4b3fc5f@mail.gmail.com> <7e0dd21a0809030338k3335a5eah4be6e27c26aecf59@mail.gmail.com> <20080903.040626.198546183.davem@davemloft.net> <7e0dd21a0809030605odc28306re8b7640f0632ac36@mail.gmail.com> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Cc: David Miller , netdev@vger.kernel.org To: Johann Baudy Return-path: Received: from relay.2ka.mipt.ru ([194.85.80.65]:54737 "EHLO 2ka.mipt.ru" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752529AbYICN2C (ORCPT ); Wed, 3 Sep 2008 09:28:02 -0400 Content-Disposition: inline In-Reply-To: <7e0dd21a0809030605odc28306re8b7640f0632ac36@mail.gmail.com> Sender: netdev-owner@vger.kernel.org List-ID: Hi Johann. On Wed, Sep 03, 2008 at 03:05:07PM +0200, Johann Baudy (johaahn@gmail.com) wrote: > TCP socket, transferring 20Mbytes file (located in initramfs) in loop > with sendfile() : 5.7Mbytes/s And _THIS_ is a serious problem. Let's assume that sendfile is broken or driver/hardware does not support scatter/gather and checksumming (does it?). Can you saturate the link with pktgen (1) and usual tcp socket (2). Assuming second case will fail, does it also broken because of very small performance of the copy from the userspace? -- Evgeniy Polyakov