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

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Message-ID: <4C03E1CD.4000809@netservers.co.uk>
Date:	Mon, 31 May 2010 17:20:29 +0100
From:	Ben McKeegan <ben@...servers.co.uk>
To:	Paul Mackerras <paulus@...ba.org>
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

Paul Mackerras 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.

Okay, I'll fix it up when I'm back at work Tuesday and submit (today is 
a UK public holiday) and also dig out and fix up the userspace code to 
go with it.

Ben.

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