From mboxrd@z Thu Jan 1 00:00:00 1970 From: Daniel Borkmann Subject: Re: Improving PACKET_{RX,TX}_RING documentation Date: Mon, 19 May 2014 12:14:58 +0200 Message-ID: <5379D9A2.1070008@redhat.com> References: <1400332406.2395.35.camel@actium.fritz.box> <53798E97.1000505@gmail.com> Mime-Version: 1.0 Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: 7bit Return-path: In-Reply-To: <53798E97.1000505-Re5JQEeQqe8AvxtiuMwx3w@public.gmane.org> Sender: linux-man-owner-u79uwXL29TY76Z2rM5mHXA@public.gmane.org To: "Michael Kerrisk (man-pages)" Cc: Carsten Andrich , linux-man-u79uwXL29TY76Z2rM5mHXA@public.gmane.org, Willem de Bruijn , Neil Horman , jbrouer-H+wXaHxf7aLQT0dZR+AlfA@public.gmane.org List-Id: linux-man@vger.kernel.org Hi Carsten, On 05/19/2014 06:54 AM, Michael Kerrisk (man-pages) wrote: > On 05/17/2014 03:13 PM, Carsten Andrich wrote: >> Hello again everyone, >> >> roughly 3 weeks ago the aftermath of an actually minor patch to fix an >> inaccuracy in packet.7's PACKET_TX_RING-related documentation led me to >> offer improving the entire PACKET_{RX,TX}_RING-documentation. >> Since I do happen to have most of my spare time back by now, I'd like to >> tackle this effort before I change my mind :) > > Thanks for following up! > >> On 04/24/2014 12:21 PM, Michael Kerrisk (man-pages) wrote: >>> I'd leave that plan largely to you. It sounds like Willem and >>> Daniel are willing to help out. >> >> I'd like to start with getting packet.7's documentation of >> PACKET_{RX,TX}_RING into a shape, that should allow most readers to >> actually use it without consulting packet_mmap.txt. The latter can be >> quite confusing for those unfamiliar with PACKET_{RX,TX}_RING. >> >> I plan to do the following to packet.7: 0. Perhaps a general writeup on how the RX/TX_RING works in Linux, it's layout, constraints etc. Btw, not sure if that's also included already, but the same mmap-technique exists also for netlink sockets. >> 1. Increase detail of PACKET_{RX,TX}_RING socket options, including >> description of struct tpacket_hdr and anything else required to >> operate the ring. >> 2. Move some details from other sockopts (e.g. PACKET_LOSS) into >> *_RING. >> 3. Add fully functional example source code for simple >> PACKET_{RX,TX}_RING operation (initialization and operation). >> This may be as much as 3 different example programs if I >> incorporate [2] and [3] in an appropriate manner. It might be a >> good idea to add a non-*_RING example as well. Yes, some examples for mmap RX, mmap TX, fanout, and perhaps TPACKET_V3 might be great. >> 4. Add a warning about inferior _TX_RING performance [1] which I >> suffered from only recently in the measurements I made for my >> thesis on Linux 3.14. Can you elaborate? Jesper made recently a nice summary on using trafgen which uses TX_RING internally: http://netoptimizer.blogspot.ch/2014/04/trafgen-fast-packet-generator.html >> 5. Other minor changes that'll come up while taking care of 1 thru >> 4 :) Absolutely, perhaps explaining differences from TPACKET_V1 -> V3 API and the like. >> Any suggestions regarding this rough course of action? > > Well, I can't speak to the fine technical details, but the plan looks > rational to me. Perhaps Neil, Willem, or Daniel has a comment. > > Just by the way, I suggest CCing netdeve-u79uwXL29TY76Z2rM5mHXA@public.gmane.org on all patches. > It may be that someone else also comments. > > Cheers, > > Michael -- To unsubscribe from this list: send the line "unsubscribe linux-man" in the body of a message to majordomo-u79uwXL29TY76Z2rM5mHXA@public.gmane.org More majordomo info at http://vger.kernel.org/majordomo-info.html