All of lore.kernel.org
 help / color / mirror / Atom feed
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?

  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

Reply instructions:

You may reply publicly to this message via plain-text email
using any one of the following methods:

* Save the following mbox file, import it into your mail client,
  and reply-to-all from there: mbox

  Avoid top-posting and favor interleaved quoting:
  https://en.wikipedia.org/wiki/Posting_style#Interleaved_style

* Reply using the --to, --cc, and --in-reply-to
  switches of git-send-email(1):

  git send-email \
    --in-reply-to=20120704165132.GA3455@nuttenaction \
    --to=hagen@jauu.net \
    --cc=aterzis@google.com \
    --cc=eric.dumazet@gmail.com \
    --cc=msg@google.com \
    --cc=netdev@vger.kernel.org \
    --cc=ycheng@google.com \
    /path/to/YOUR_REPLY

  https://kernel.org/pub/software/scm/git/docs/git-send-email.html

* If your mail client supports setting the In-Reply-To header
  via mailto: links, try the mailto: link
Be sure your reply has a Subject: header at the top and a blank line before the message body. 
This is an external index of several public inboxes,
see mirroring instructions on how to clone and mirror
all data and code used by this external index.