From mboxrd@z Thu Jan  1 00:00:00 1970
From: Eric Dumazet <eric.dumazet@gmail.com>
Subject: Re: Bad shaping at low rates, after commit 56b765b79 (htb: improved
 accuracy at high rates)
Date: Tue, 04 Jun 2013 08:18:53 -0700
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	 <20130604141342.00c8eb9f@redhat.com>
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Cc: Stephen Hemminger <stephen@networkplumber.org>,
	Jiri Benc <jbenc@redhat.com>, David Miller <davem@redhat.com>,
	j.vimal@gmail.com, Michal Soltys <soltys@ziu.info>,
	Mike Frysinger <vapier@gentoo.org>,
	Jussi Kivilinna <jussi.kivilinna@mbnet.fi>,
	Patrick McHardy <kaber@trash.net>,
	Jiri Pirko <jpirko@redhat.com>,
	Toke =?ISO-8859-1?Q?H=F8iland-J=F8rgensen?= <toke@toke.dk>,
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	bloat@lists.bufferbloat.net, Dan Siemon <dan@coverfire.com>,
	Jim Gettys <jg@freedesktop.org>,
	Steven Barth <cyrus@openwrt.org>, Felix Fietkau <nbd@nbd.name>
To: Jesper Dangaard Brouer <brouer@redhat.com>
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On Tue, 2013-06-04 at 14:13 +0200, Jesper Dangaard Brouer wrote:
> Hi again,
> 
> I found another regression by commit 56b765b79 (htb: improved accuracy
> at high rates).
> 
> After the commit HTB does not honor network rate limiting below 500kbps.
> 
> I have found that the bandwidth problem is related to GSO being enabled
> on the device.  To test the situation, I had to use a real NIC (as I
> were not allowed to disable GSO on dev "lo", test below).

Well, do not forget lo mtu is 64K, so you'll also have to lower it for
your tests.

I have a good idea of what's going on for htb at low rates, I am testing
a fix, thanks for the report !