From: Jesper Dangaard Brouer <jbrouer-H+wXaHxf7aLQT0dZR+AlfA@public.gmane.org>
To: Carsten Andrich
<carsten.andrich-hs6bpBdVsEZfm0AUMx9V0g@public.gmane.org>
Cc: Willem de Bruijn
<willemb-hpIqsD4AKlfQT0dZR+AlfA@public.gmane.org>,
Daniel Borkmann
<dborkman-H+wXaHxf7aLQT0dZR+AlfA@public.gmane.org>,
"Michael Kerrisk (man-pages)"
<mtk.manpages-Re5JQEeQqe8AvxtiuMwx3w@public.gmane.org>,
linux-man-u79uwXL29TY76Z2rM5mHXA@public.gmane.org,
Neil Horman <nhorman-2XuSBdqkA4R54TAoqtyWWQ@public.gmane.org>
Subject: Re: Improving PACKET_{RX,TX}_RING documentation
Date: Thu, 22 May 2014 15:37:55 +0200 [thread overview]
Message-ID: <20140522153755.13aa7f5a@redhat.com> (raw)
In-Reply-To: <d1afaaacb05c031517bb96211c098edf@localhost>
On Thu, 22 May 2014 14:22:22 +0200 Carsten Andrich <carsten.andrich-hs6bpBdVsEZfm0AUMx9V0g@public.gmane.org> wrote:
> Using positive wording is always a good idea, but packet_mmap.txt
> already tricked me into believing that PACKET_TX_RING should be faster
> than plain sendto(). The user should be allowed to make an informed
> decision, which requires the manpage to tell the (ugly) truth that
> sendto() currently outperforms TX_RING.
See:
https://github.com/netsniff-ng/netsniff-ng/commit/d21b30bd64fdf4e7358037aa2d6f0cea02c49b6e
With most recent trafgen using small packets, TX_RING version is faster than sendto().
> > The optimization you refer to is to attach the tx-only packet socket
> > to a protocol family that is never observed, so that no packets are
> > looped back into the socket on receive. This is a great trick. There
> > are probably others. Again, I believe that such details belong more in
> > packet_mmap.txt than in the man page. But that is just one opinion, so
> > I'll gladly defer to Michael and others on that point.
See commit, on how to avoid the packet_rcv() call:
https://github.com/netsniff-ng/netsniff-ng/commit/c3602a995b21e8133c7f
It differs a little sendto() vs. TX_RING setup.
--
Best regards,
Jesper Dangaard Brouer
MSc.CS, Sr. Network Kernel Developer at Red Hat
Author of http://www.iptv-analyzer.org
LinkedIn: http://www.linkedin.com/in/brouer
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next prev parent reply other threads:[~2014-05-22 13:37 UTC|newest]
Thread overview: 10+ messages / expand[flat|nested] mbox.gz Atom feed top
2014-05-17 13:13 Improving PACKET_{RX,TX}_RING documentation Carsten Andrich
[not found] ` <1400332406.2395.35.camel-FQO4gtnRtnzkVFMGpb/cPg@public.gmane.org>
2014-05-19 4:54 ` Michael Kerrisk (man-pages)
[not found] ` <53798E97.1000505-Re5JQEeQqe8AvxtiuMwx3w@public.gmane.org>
2014-05-19 10:14 ` Daniel Borkmann
[not found] ` <5379D9A2.1070008-H+wXaHxf7aLQT0dZR+AlfA@public.gmane.org>
2014-05-19 15:05 ` Willem de Bruijn
[not found] ` <CA+FuTSeWh_iQGqc-4usL7vr28OrkHTnBvHvXvVO=LcGsNRgtMA-JsoAwUIsXosN+BqQ9rBEUg@public.gmane.org>
2014-05-19 16:01 ` Daniel Borkmann
2014-05-22 12:22 ` Carsten Andrich
2014-05-22 13:13 ` Michael Kerrisk (man-pages)
2014-05-22 13:37 ` Jesper Dangaard Brouer [this message]
2014-05-22 14:51 ` Willem de Bruijn
[not found] ` <CA+FuTSfpORKtm_kdG+CycoPiq+Gxf58=nXqKApFEmR+xZs69_g-JsoAwUIsXosN+BqQ9rBEUg@public.gmane.org>
2014-05-26 10:49 ` Carsten Andrich
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