From: "Steinar H. Gunderson" <sgunderson@bigfoot.com>
To: Jesper Dangaard Brouer <jbrouer@redhat.com>
Cc: "Eric Dumazet" <eric.dumazet@gmail.com>,
"Toke Høiland-Jørgensen" <toke@toke.dk>,
"Mike Frysinger" <vapier@gentoo.org>,
"Jiri Benc" <jbenc@redhat.com>, "Jiri Pirko" <jpirko@redhat.com>,
netdev@vger.kernel.org, bloat@lists.bufferbloat.net,
"Patrick McHardy" <kaber@trash.net>,
"Steven Barth" <cyrus@openwrt.org>,
"russell-tcatm@stuart.id.au" <russell-tcatm@stuart.id.au>,
"David Miller" <davem@redhat.com>,
"Jussi Kivilinna" <jussi.kivilinna@mbnet.fi>,
"Felix Fietkau" <nbd@nbd.name>, "Michal Soltys" <soltys@ziu.info>
Subject: Re: [Bloat] tc linklayer ADSL calc broken after commit 56b765b79 (htb: improved accuracy at high rates)
Date: Thu, 30 May 2013 11:52:53 +0200 [thread overview]
Message-ID: <20130530095253.GA8461@uio.no> (raw)
In-Reply-To: <20130530111547.07397287@redhat.com>
On Thu, May 30, 2013 at 11:15:47AM +0200, Jesper Dangaard Brouer wrote:
> int pkt_len = skb->len + (encap_overhead * gso_segments);
> int wire_sz = DIV_ROUND_UP(pkt_len,48)*53;
>
> (I suspect, that the compiler might even optimize and remove any
> real divisions, I bet Eric can tell us.)
FWIW, GCC can change divisions by integer constants (even signed divisions)
to some multiplies and shifts, by way of some number theory magic.
/* Steinar */
--
Homepage: http://www.sesse.net/
next prev parent reply other threads:[~2013-05-30 9:53 UTC|newest]
Thread overview: 35+ messages / expand[flat|nested] mbox.gz Atom feed top
2013-05-29 13:13 tc linklayer ADSL calc broken after commit 56b765b79 (htb: improved accuracy at high rates) Jesper Dangaard Brouer
2013-05-29 15:52 ` Eric Dumazet
2013-05-29 22:50 ` Stephen Hemminger
2013-05-29 23:18 ` Eric Dumazet
2013-05-30 9:15 ` Jesper Dangaard Brouer
2013-05-30 9:52 ` Steinar H. Gunderson [this message]
[not found] ` <20130529155034.334092c5-We1ePj4FEcvRI77zikRAJc56i+j3xesD0e7PPNI6Mm0@public.gmane.org>
2013-05-30 0:34 ` Dave Taht
2013-05-30 8:09 ` Jesper Dangaard Brouer
2013-05-30 7:51 ` Jesper Dangaard Brouer
2013-05-30 14:39 ` Eric Dumazet
2013-05-30 15:55 ` Jesper Dangaard Brouer
2013-05-30 16:29 ` Jussi Kivilinna
2013-06-02 21:15 ` Eric Dumazet
2013-06-02 21:33 ` [PATCH iproute2] htb: report overhead attribute Eric Dumazet
2013-06-03 15:45 ` Rick Jones
2013-06-03 15:56 ` Eric Dumazet
2013-06-04 11:11 ` Jesper Dangaard Brouer
2013-06-04 13:58 ` Eric Dumazet
2013-06-04 15:08 ` Jesper Dangaard Brouer
2013-06-03 19:50 ` Jussi Kivilinna
2013-06-07 15:56 ` Stephen Hemminger
2013-06-07 16:00 ` Eric Dumazet
2013-06-04 12:13 ` Bad shaping at low rates, after commit 56b765b79 (htb: improved accuracy at high rates) Jesper Dangaard Brouer
2013-06-04 15:18 ` Eric Dumazet
2013-06-04 15:55 ` Eric Dumazet
2013-06-04 16:02 ` Eric Dumazet
2013-06-04 17:11 ` [PATCH] net_sched: htb: do not mix 1ns and 64ns time units Eric Dumazet
2013-06-04 20:21 ` Jesper Dangaard Brouer
[not found] ` <20130604222135.67eedab8-H+wXaHxf7aLQT0dZR+AlfA@public.gmane.org>
2013-06-04 20:26 ` Dave Taht
2013-06-04 21:02 ` Eric Dumazet
2013-06-04 20:50 ` Eric Dumazet
2013-06-05 0:44 ` David Miller
2013-06-06 13:55 ` RFC: Proposed fix for tc linklayer calc broken after commit 56b765b79 (htb: improved accuracy at high rates) Jesper Dangaard Brouer
2013-06-06 14:28 ` Eric Dumazet
-- strict thread matches above, loose matches on Subject: below --
2013-05-30 4:20 [Bloat] tc linklayer ADSL " Hagen Paul Pfeifer
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