linux-kernel - Re: [Patch] fix packet loss and massive ping spikes with PPP multi-link

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Message-ID: <20100529021624.GA2538@brick.ozlabs.ibm.com>
Date:	Sat, 29 May 2010 12:16:24 +1000
From:	Paul Mackerras <paulus@...ba.org>
To:	Ben McKeegan <ben@...servers.co.uk>
Cc:	netdev@...r.kernel.org, linux-ppp@...r.kernel.org,
	Alan Cox <alan@...rguk.ukuu.org.uk>,
	"Alexander E. Patrakov" <patrakov@...il.com>,
	Richard Hartmann <richih.mailinglist@...il.com>,
	linux-kernel@...r.kernel.org
Subject: Re: [Patch] fix packet loss and massive ping spikes with PPP
 multi-link

On Wed, Mar 31, 2010 at 11:03:44AM +0100, Ben McKeegan wrote:

> I needed to do something similar a while back and I took a very
> different approach, which I think is more flexible.   Rather than
> implement a new round-robin scheduler I simply introduced a target
> minimum fragment size into the fragment size calculation, as a per
> bundle parameter that can be configured via a new ioctl.  This
> modifies the algorithm so that it tries to limit the number of
> fragments such that each fragment is at least the minimum size.  If
> the minimum size is greater than the packet size it will not be
> fragmented all but will instead just get sent down the next
> available channel.
> 
> A pppd plugin generates the ioctl call allowing this to be tweaked
> per connection.  It is more flexible in that you can still have the
> larger packets fragmented if you wish.

I like this a lot better than the other proposed patch.  It adds less
code because it uses the fact that ppp_mp_explode() already has a
round-robin capability using the ppp->nxchan field, plus it provides a
way to control it per bundle via pppd.

If you fix up the indentation issues (2-space indent in some of the
added code -- if you're using emacs, set c-basic-offset to 8), I'll
ack it and hopefully DaveM will pick it up.

Paul.
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