From mboxrd@z Thu Jan 1 00:00:00 1970 From: "Johann Baudy" Subject: Re: Fwd: Packet mmap: TX RING and zero copy Date: Fri, 5 Sep 2008 15:55:14 +0200 Message-ID: <7e0dd21a0809050655n176ec32bo2bf4febe4e0fc363@mail.gmail.com> References: <7e0dd21a0809031330i1363c4aema9c57ef06a3d5279@mail.gmail.com> <7e0dd21a0809040744q3ee65695uc33f6cc26a1fe4dd@mail.gmail.com> <20080905071754.GA25998@2ka.mipt.ru> <7e0dd21a0809050216r65b8f08fm1ad0630790a13a54@mail.gmail.com> <7e0dd21a0809050217v33ecb8fvcadd5e65118d6afe@mail.gmail.com> <20080905113112.GA29926@2ka.mipt.ru> <7e0dd21a0809050544m47deaf0dsf1f31805890ac09@mail.gmail.com> <20080905131618.GB12246@2ka.mipt.ru> <7e0dd21a0809050629w7fa8a914i863faa9ac18c3be4@mail.gmail.com> <20080905133748.GA28656@2ka.mipt.ru> Mime-Version: 1.0 Content-Type: text/plain; charset=ISO-8859-1 Content-Transfer-Encoding: 7bit Cc: netdev@vger.kernel.org To: "Evgeniy Polyakov" Return-path: Received: from rv-out-0506.google.com ([209.85.198.238]:52579 "EHLO rv-out-0506.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1753107AbYIENzP (ORCPT ); Fri, 5 Sep 2008 09:55:15 -0400 Received: by rv-out-0506.google.com with SMTP id k40so462443rvb.1 for ; Fri, 05 Sep 2008 06:55:14 -0700 (PDT) In-Reply-To: <20080905133748.GA28656@2ka.mipt.ru> Content-Disposition: inline Sender: netdev-owner@vger.kernel.org List-ID: Hi Evgeniy, > That's a bug. Likely no one sends file content via udp, so it was not > detected... Ok, I'll will run a FTRACE of this issue on monday; >> I will try to investigate it but for my app sendfile() is not >> conceivable. Only vmsplice could, but too slow. > > Well, you can mmap empty file into the RAM, lock it there, DMA data from > the sensor to the mmapped area, add headers (just in the mapped area) > and then sendfile that file.. Single syscall, zero-copy, standard > interfaces :) > OK but it seems that there is no way to control packet format. (beginning of packet and size of packet). Each packet must start with a specific header (on my app). This is a kind of streaming. Thanks, Johann -- Johann Baudy johaahn@gmail.com