netdev - Re: [Netem] Fixed delay patch for netem

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Message-ID: <682bc30a0802260345w676f4339v3c5742e1f0bad1fd@mail.gmail.com>
Date:	Tue, 26 Feb 2008 09:45:31 -0200
From:	"Julio Kriger" <juliokriger@...il.com>
To:	"Stephen Hemminger" <shemminger@...ux-foundation.org>
Cc:	netdev@...r.kernel.org, netdev@....sgi.com,
	netem@...ux-foundation.org, netem@...ts.linux-foundation.org
Subject: Re: [Netem] Fixed delay patch for netem

Hi Stephen,
Answering your question: there is no diffence if (and only if) there
is no gap reordering. If there is gap reordering then packets will get
a delay of 0ms or 80ms +/- 15ms. With the patch I sent,  packets will
get a delay of 50ms or 80ms +/- 15ms.
I have read about other network emulators, like NS-2, and they have
the option of gap reordering.
As I say, I need a fixed delay of 50ms plus all the other usefull
stuff that comes with netem. And netem does not allow be nested with
himself.
Regards,
Julio


On 2/25/08, Stephen Hemminger <shemminger@...ux-foundation.org> wrote:
> On Sun, 24 Feb 2008 12:11:16 -0200
> "Julio Kriger" <juliokriger@...il.com> wrote:
>
> > Hi!
> > I have created this patch to add a fixed delay on packet filtered by
> > netem. Soon I will send the patch to iproute2.
> > This patch comes from a need I have to delay all packets 50ms, beside
> > the actual delay setting, like 30ms +- 15 ms.
>
> Why is 50ms + 30m +/- 15ms any different than 80ms +/- 15ms
>
> > This strike, IMMHO, a
> > missing point on gap reordering. If I set "gap 5 delay 10ms" every 5th
> > (10th, 15th, ...) packet to go to be sent immediately and every other
> > packet to be delayed by 10ms. This  is ok, but I also need a "fixed"
> > delay of 50ms to be applied to all packets. Since netem can't be
> > nested with himself (so I can do a fixed delay), I needed this new
> > feature on netem.
>
> The gap stuff is an awkward interface that should/could have been
> done better.
>
> > This patch was create with linux kernel version 2.6.24.2.
> > I hope you like it, and it would be great if it goes shiped with the
> > next version of the kernel :-))
> > Regards,
> > Julio Kriger
>
> Maybe, but it is getting confusing with all the growth of parameters.
> Probably time for a rethink.
>


-- 
--
>From the moment I picked your book up until I laid it down, I was
convulsed with laughter. Someday I intend reading it.
Groucho Marx
----------------------------
Julio Kriger
mailto:juliokriger@...il.com
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