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Re: [manet] next version of pause extension

Rick Taylor <rick@tropicalstormsoftware.com> Thu, 09 November 2017 16:11 UTC

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From: Rick Taylor <rick@tropicalstormsoftware.com>
To: Henning Rogge <hrogge@gmail.com>, Lou Berger <lberger@labn.net>
CC: "manet@ietf.org" <manet@ietf.org>
Thread-Topic: [manet] next version of pause extension
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Date: Thu, 09 Nov 2017 16:10:26 +0000
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Subject: Re: [manet] next version of pause extension
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Comments inline...

> -----Original Message-----
> From: Henning Rogge [mailto:hrogge@gmail.com]
> Sent: 09 November 2017 12:03
> To: Lou Berger
> Cc: Rick Taylor; manet@ietf.org
> Subject: Re: [manet] next version of pause extension
> 
> On Wed, Nov 8, 2017 at 3:56 PM, Lou Berger <lberger@labn.net> wrote:
> > I really view Pause and Credit as having different use cases.  The
> > first is fairly simple to implement but is likely to be inefficient,
> > i.e., result in periods of time when the link is idle.  The second is
> > far more powerful and complex to implement, but is likely to be more
> > efficient
> > *and* allow a smart router to make more sophisticated decisions based
> > on window sizes.
> 
> Unfortunately Pause (at least with Linux) is not that great to use...
> it works with some cards, it doesn't works with different cards and
> sometimes it behaves strange.
> 
> We experimented with it but have yet to test it combined with VLAN TOS
> IDs.
> 
> Unfortunately I have yet to find a good way to implement something like the
> credit extension without extending the Linux Kernel, so this is even worse to
> implement.
> 
> (Tips and Hints welcome!)

I would suggest the answer lives somewhere in the ethtool API, but it's a weird backwater of the kernel that doesn't see much love.  I don't think one can avoid kernel patches.

Rick

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