From: Hagen Paul Pfeifer <hagen@jauu.net>
To: Eric Dumazet <eric.dumazet@gmail.com>
Cc: netdev <netdev@vger.kernel.org>,
Yuchung Cheng <ycheng@google.com>,
Andreas Terzis <aterzis@google.com>, Mark Gordon <msg@google.com>
Subject: Re: [PATCH] netem: fix rate extension and drop accounting
Date: Wed, 4 Jul 2012 18:51:32 +0200 [thread overview]
Message-ID: <20120704165132.GA3455@nuttenaction> (raw)
In-Reply-To: <1341381488.2583.1395.camel@edumazet-glaptop>
* Eric Dumazet | 2012-07-04 07:58:08 [+0200]:
>DEV=eth0
>tc qdisc del dev $DEV root
>tc qdisc add dev $DEV root handle 30: est 1sec 4sec netem \
> delay 100ms 10ms reorder 3
>tc qdisc add dev $DEV handle 40:0 parent 30:0 tbf \
> burst 5000 limit 10000 mtu 1514 rate 100kbit
>tc qdisc add dev $DEV handle 50:00 parent 40:0 pfifo limit 200
>
>fundamentally, mixing the TBF is going to be hard with "delay ..."
>especially with jitter.
>
>Same problem for reorder : since packets are put at head of queue,
>they have no effect on the 'time_to_send' of packets already in queue
>and netem use more bandwidth than allowed.
>
>I'll send the patch on the double drop accounting problem because the
>fix is easy enough, but fir the rate limiting, I prefer letting you work
>on it if you dont mind ?
OK, I will work on it tomorrow! But Eric, keep in mind that this accumulative
behavior is intended: think about a hypothetical satellite link with a
bandwidth (rate) of 1000 byte/s. If you send three 1000 byte consecutively
packets. The first packet is delayed for 1 second, the second then is
transmitted after 2 seconds, the third after three seconds and so on. So
_this_ accumulative behavior is correct. Anyway, I will look at this tomorrow!
Thanks Eric!
PS: one last question: what do you want to test? TBF and netem rate at the
same time looks, mmhh, special ... ;-) I ask myself what link exhibit this
characteristic?
next prev parent reply other threads:[~2012-07-04 16:51 UTC|newest]
Thread overview: 10+ messages / expand[flat|nested] mbox.gz Atom feed top
2012-07-03 9:25 [PATCH] netem: fix rate extension and drop accounting Eric Dumazet
2012-07-03 9:54 ` Eric Dumazet
2012-07-03 22:04 ` Hagen Paul Pfeifer
2012-07-04 5:58 ` Eric Dumazet
2012-07-04 16:51 ` Hagen Paul Pfeifer [this message]
2012-07-04 17:23 ` Eric Dumazet
2012-07-04 17:30 ` Hagen Paul Pfeifer
[not found] ` <CAPVr9VP7DniPZj4vZi_myJWfL5JLYKYTXXtrXcKHo9LjEQzjYw@mail.gmail.com>
2012-07-16 23:26 ` Hagen Paul Pfeifer
2012-07-17 5:12 ` Eric Dumazet
[not found] ` <CAPVr9VMCYFO-7uEzO6ft2vpPhVvRgHB3EWJJG62OqGqux1LsZQ@mail.gmail.com>
2012-07-17 17:39 ` Eric Dumazet
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