netdev - Re: [PATCH] netem: fix rate extension and drop accounting

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite: Windows password security audit tool. GUI, reports in PDF.

[<prev] [next>] [<thread-prev] [thread-next>] [day] [month] [year] [list]

Message-ID: <1341422601.2583.2393.camel@edumazet-glaptop>
Date:	Wed, 04 Jul 2012 19:23:21 +0200
From:	Eric Dumazet <eric.dumazet@...il.com>
To:	Hagen Paul Pfeifer <hagen@...u.net>
Cc:	netdev <netdev@...r.kernel.org>, Yuchung Cheng <ycheng@...gle.com>,
	Andreas Terzis <aterzis@...gle.com>,
	Mark Gordon <msg@...gle.com>
Subject: Re: [PATCH] netem: fix rate extension and drop accounting

On Wed, 2012-07-04 at 18:51 +0200, Hagen Paul Pfeifer wrote:
> 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!
> 

I fear you did your tests with no delay on netem.

Try to setup a rate of 100kbit and a delay of 100ms and to really get
full bandwith (100kbit), I am afraid it doesnt work.

Your algo is OK only if no packets are in queue (obviously)

But if you have 2 or 3 packets, the delay are cumulative,
but the delay should be a fixed bias for each packet.


> 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?

TBF as a netem child was the usual way to have delay + rate before your
patch ?

Not sure why you find it special ?


--
To unsubscribe from this list: send the line "unsubscribe netdev" in
the body of a message to majordomo@...r.kernel.org
More majordomo info at  http://vger.kernel.org/majordomo-info.html