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Re: [very-RFC 0/8] TSN driver for the kernel

From Henrik Austad <henrik@austad.us>
Newsgroups linux.kernel
Subject Re: [very-RFC 0/8] TSN driver for the kernel
Date 2016-06-14 10:40 +0200
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References <rJ0cp-QL-3@gated-at.bofh.it> <rJyxr-5JN-5@gated-at.bofh.it> <rJCro-8ke-35@gated-at.bofh.it>
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On Mon, Jun 13, 2016 at 08:56:44AM -0700, John Fastabend wrote:
> On 16-06-13 04:47 AM, Richard Cochran wrote:
> > [...]
> > Here is what is missing to support audio TSN:
> > 
> > * User Space
> > 
> > 1. A proper userland stack for AVDECC, MAAP, FQTSS, and so on.  The
> >    OpenAVB project does not offer much beyond simple examples.
> > 
> > 2. A user space audio application that puts it all together, making
> >    use of the services in #1, the linuxptp gPTP service, the ALSA
> >    services, and the network connections.  This program will have all
> >    the knowledge about packet formats, AV encodings, and the local HW
> >    capabilities.  This program cannot yet be written, as we still need
> >    some kernel work in the audio and networking subsystems.
> > 
> > * Kernel Space
> > 
> > 1. Providing frames with a future transmit time.  For normal sockets,
> >    this can be in the CMESG data.  For mmap'ed buffers, we will need a
> >    new format.  (I think Arnd is working on a new layout.)
> > 
> > 2. Time based qdisc for transmitted frames.  For MACs that support
> >    this (like the i210), we only have to place the frame into the
> >    correct queue.  For normal HW, we want to be able to reserve a time
> >    window in which non-TSN frames are blocked.  This is some work, but
> >    in the end it should be a generic solution that not only works
> >    "perfectly" with TSN HW but also provides best effort service using
> >    any NIC.
> > 
> 
> When I looked at this awhile ago I convinced myself that it could fit
> fairly well into the DCB stack (DCB is also part of 802.1Q). A lot of
> the traffic class to queue mappings and priories could be handled here.
> It might be worth taking a look at ./net/sched/mqprio.c and ./net/dcb/.

Interesting, I'll have a look at dcb and mqprio, I'm not familiar with 
those systems. Thanks for pointing those out!

I hope that the complexity doesn't run crazy though, TSN is not aimed at 
datacentra, a lot of the endpoints are going to be embedded devices, 
introducing a massive stack for handling every eventuality in 802.1q is 
going to be counter productive.

> Unfortunately I didn't get too far along but we probably don't want
> another mechanism to map hw queues/tcs/etc if the existing interfaces
> work or can be extended to support this.

Sure, I get that, as long as the complexity for setting up a link doesn't 
go through the roof :)

Thanks!

-- 
Henrik Austad

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Thread

[very-RFC 0/8] TSN driver for the kernel Henrik Austad <henrik@austad.us> - 2016-06-12 01:10 +0200
  [very-RFC 1/8] TSN: add documentation Henrik Austad <henrik@austad.us> - 2016-06-12 01:10 +0200
  [very-RFC 3/8] Adding TSN-driver to Intel I210 controller Henrik Austad <henrik@austad.us> - 2016-06-12 01:10 +0200
  [very-RFC 6/8] Add TSN event-tracing Henrik Austad <henrik@austad.us> - 2016-06-12 01:10 +0200
    Re: [very-RFC 6/8] Add TSN event-tracing Steven Rostedt <rostedt@goodmis.org> - 2016-06-12 19:00 +0200
      Re: [very-RFC 6/8] Add TSN event-tracing Henrik Austad <henrik@austad.us> - 2016-06-12 23:30 +0200
        Re: [very-RFC 6/8] Add TSN event-tracing Steven Rostedt <rostedt@goodmis.org> - 2016-06-13 04:30 +0200
          Re: [very-RFC 6/8] Add TSN event-tracing Henrik Austad <henrik@austad.us> - 2016-06-13 09:30 +0200
  [very-RFC 8/8] MAINTAINERS: add TSN/AVB-entries Henrik Austad <henrik@austad.us> - 2016-06-12 01:10 +0200
  Re: [very-RFC 0/8] TSN driver for the kernel Richard Cochran <richardcochran@gmail.com> - 2016-06-13 13:50 +0200
    Re: [very-RFC 0/8] TSN driver for the kernel Henrik Austad <henrik@austad.us> - 2016-06-13 15:10 +0200
      Re: [very-RFC 0/8] TSN driver for the kernel Richard Cochran <richardcochran@gmail.com> - 2016-06-13 21:40 +0200
        Re: [very-RFC 0/8] TSN driver for the kernel Henrik Austad <henrik@austad.us> - 2016-06-14 11:40 +0200
          Re: [very-RFC 0/8] TSN driver for the kernel Richard Cochran <richardcochran@gmail.com> - 2016-06-14 20:30 +0200
            Re: [very-RFC 0/8] TSN driver for the kernel Henrik Austad <henrik@austad.us> - 2016-06-14 22:40 +0200
              Re: [very-RFC 0/8] TSN driver for the kernel Richard Cochran <richardcochran@gmail.com> - 2016-06-15 09:10 +0200
                Re: [very-RFC 0/8] TSN driver for the kernel Henrik Austad <henrik@austad.us> - 2016-06-15 10:00 +0200
                Re: [very-RFC 0/8] TSN driver for the kernel Richard Cochran <richardcochran@gmail.com> - 2016-06-15 13:50 +0200
              Re: [very-RFC 0/8] TSN driver for the kernel Richard Cochran <richardcochran@gmail.com> - 2016-06-15 09:20 +0200
      Re: [very-RFC 0/8] TSN driver for the kernel Richard Cochran <richardcochran@gmail.com> - 2016-06-13 21:40 +0200
    Re: [very-RFC 0/8] TSN driver for the kernel Arnd Bergmann <arnd@linaro.org> - 2016-06-13 15:20 +0200
    Re: [very-RFC 0/8] TSN driver for the kernel John Fastabend <john.fastabend@gmail.com> - 2016-06-13 18:00 +0200
      Re: [very-RFC 0/8] TSN driver for the kernel Henrik Austad <henrik@austad.us> - 2016-06-14 10:40 +0200
    Re: [very-RFC 0/8] TSN driver for the kernel Richard Cochran <richardcochran@gmail.com> - 2016-06-13 22:00 +0200
      Re: [very-RFC 0/8] TSN driver for the kernel One Thousand Gnomes <gnomes@lxorguk.ukuu.org.uk> - 2016-06-14 13:20 +0200
        Re: [very-RFC 0/8] TSN driver for the kernel Richard Cochran <richardcochran@gmail.com> - 2016-06-14 19:10 +0200
        Re: [very-RFC 0/8] TSN driver for the kernel Takashi Sakamoto <o-takashi@sakamocchi.jp> - 2016-06-15 05:30 +0200
          Re: [very-RFC 0/8] TSN driver for the kernel Richard Cochran <richardcochran@gmail.com> - 2016-06-15 10:10 +0200
            Re: [very-RFC 0/8] TSN driver for the kernel Takashi Sakamoto <o-takashi@sakamocchi.jp> - 2016-06-18 07:30 +0200
              Re: [very-RFC 0/8] TSN driver for the kernel Henrik Austad <henrik@austad.us> - 2016-06-19 00:50 +0200
                Re: [very-RFC 0/8] TSN driver for the kernel Richard Cochran <richardcochran@gmail.com> - 2016-06-19 11:50 +0200
                Re: [very-RFC 0/8] TSN driver for the kernel Henrik Austad <henrik@austad.us> - 2016-06-20 11:50 +0200
                Re: [alsa-devel] [very-RFC 0/8] TSN driver for the kernel Pierre-Louis Bossart <pierre-louis.bossart@linux.intel.com> - 2016-06-20 13:20 +0200
                Re: [alsa-devel] [very-RFC 0/8] TSN driver for the kernel Henrik Austad <henrik@austad.us> - 2016-06-20 14:00 +0200
                Re: [alsa-devel] [very-RFC 0/8] TSN driver for the kernel Richard Cochran <richardcochran@gmail.com> - 2016-06-20 14:30 +0200
                Re: [alsa-devel] [very-RFC 0/8] TSN driver for the kernel Richard Cochran <richardcochran@gmail.com> - 2016-06-20 15:00 +0200
                Re: [alsa-devel] [very-RFC 0/8] TSN driver for the kernel Richard Cochran <richardcochran@gmail.com> - 2016-06-20 17:40 +0200
                Re: [alsa-devel] [very-RFC 0/8] TSN driver for the kernel Takashi Iwai <tiwai@suse.de> - 2016-06-21 08:00 +0200
                Re: [alsa-devel] [very-RFC 0/8] TSN driver for the kernel Richard Cochran <richardcochran@gmail.com> - 2016-06-21 08:40 +0200
                Re: [alsa-devel] [very-RFC 0/8] TSN driver for the kernel Takashi Iwai <tiwai@suse.de> - 2016-06-21 08:50 +0200
                Re: [alsa-devel] [very-RFC 0/8] TSN driver for the kernel Pierre-Louis Bossart <pierre-louis.bossart@linux.intel.com> - 2016-06-21 19:20 +0200
                Re: [alsa-devel] [very-RFC 0/8] TSN driver for the kernel Pierre-Louis Bossart <pierre-louis.bossart@linux.intel.com> - 2016-06-21 19:50 +0200
                Re: [alsa-devel] [very-RFC 0/8] TSN driver for the kernel Richard Cochran <richardcochran@gmail.com> - 2016-06-21 23:20 +0200
                Re: [alsa-devel] [very-RFC 0/8] TSN driver for the kernel Pierre-Louis Bossart <pierre-louis.bossart@linux.intel.com> - 2016-06-22 14:40 +0200
                Re: [alsa-devel] [very-RFC 0/8] TSN driver for the kernel Henrik Austad <henrik@austad.us> - 2016-06-23 12:40 +0200
                Re: [alsa-devel] [very-RFC 0/8] TSN driver for the kernel Richard Cochran <richardcochran@gmail.com> - 2016-06-23 15:30 +0200
        Re: [very-RFC 0/8] TSN driver for the kernel Takashi Sakamoto <o-takashi@sakamocchi.jp> - 2016-06-15 05:30 +0200

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