From mboxrd@z Thu Jan  1 00:00:00 1970
From: "Steinar H. Gunderson" <sgunderson@bigfoot.com>
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
Message-ID: <20130530095253.GA8461@uio.no>
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Cc: Eric Dumazet <eric.dumazet@gmail.com>,
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	Mike Frysinger <vapier@gentoo.org>,
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	Patrick McHardy <kaber@trash.net>,
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	David Miller <davem@redhat.com>,
	Jussi Kivilinna <jussi.kivilinna@mbnet.fi>,
	Felix Fietkau <nbd@nbd.name>, Michal Soltys <soltys@ziu.info>
To: Jesper Dangaard Brouer <jbrouer@redhat.com>
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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/