netdev - Re: [PATCH v2 2/2] net: netem: always adjust now/delay when not reordering

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Date:	Wed, 21 Aug 2013 06:30:24 -0700
From:	Eric Dumazet <eric.dumazet@...il.com>
To:	Ferry Huberts <mailings@...ie.com>
Cc:	netdev@...r.kernel.org
Subject: Re: [PATCH v2 2/2] net: netem: always adjust now/delay when not
 reordering

On Wed, 2013-08-21 at 09:04 +0200, Ferry Huberts wrote:
> 
> On 21/08/13 08:14, Eric Dumazet wrote:
> > On Wed, 2013-08-21 at 07:59 +0200, Ferry Huberts wrote:
> >> From: Ferry Huberts <ferry.huberts@...agic.nl>
> >>
> >> Not doing this (current behaviour) introduces reordering.
> >>
> >> The packet_len_2_sched_time call is the only thing that logically
> >> depends on q->rate, so move the now/delay adjustment out of the if.
> >>
> >> How to test:
> >> -----------
> > 
> > I ask again :
> > 
> > Did you test a config with both rate limiting and delay.
> 
> (sorry for missing that question)
> 
> Just did so and with rate limiting I get no reordering, which is logical
> looking at the code.
> 
> The thing is, the evaluation q->rate is within the 'no-reordering' block
> and in the current situation you can get reordering (with that 'strange'
> command). My patch makes sure that no reordering will occur, and
> effectively 'clamps' the realised delay, which currently isn't done.


OK, let me be very clear.

I would like you post the results of regression tests, to make sure that
you do not add a new regression.

It seems that you want _us_ to check all this for you.

With "rate 1Mbits delay 100ms 10ms", and ping probes sent every 100ms,
the pong reply of _all_ probes should be between 90ms and 110ms

Is it still the case after your patch ?

Thanks


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