From: "Jörn Engel" <joern@wohnheim.fh-wedel.de>
To: Anton Blanchard <anton@samba.org>
Cc: Jan-Bernd Themann <ossthema@de.ibm.com>,
netdev <netdev@vger.kernel.org>,
linux-ppc <linuxppc-dev@ozlabs.org>,
linux-kernel <linux-kernel@vger.kernel.org>,
Marcus Eder <meder@de.ibm.com>,
Christoph Raisch <raisch@de.ibm.com>,
Thomas Klein <tklein@de.ibm.com>
Subject: Re: [PATCH 1/6] ehea: interface to network stack
Date: Mon, 14 Aug 2006 13:26:56 +0200 [thread overview]
Message-ID: <20060814112656.GC10164@wohnheim.fh-wedel.de> (raw)
In-Reply-To: <20060811205624.GE479@krispykreme>
On Sat, 12 August 2006 06:56:24 +1000, Anton Blanchard wrote:
>
> > +
> > + skb_index = ((index - i
> > + + port_res->skb_arr_sq_len)
> > + % port_res->skb_arr_sq_len);
>
> This is going to force an expensive divide. Its much better to change
> this to the simpler and quicker:
>
> i++;
> if (i > max)
> i = 0;
Is a conditional cheaper than a divide? In case of a misprediction I
would assume it to be significantly slower and I don't know the ratio
of mispredictions for this branch.
Jörn
--
Victory in war is not repetitious.
-- Sun Tzu
next prev parent reply other threads:[~2006-08-14 11:27 UTC|newest]
Thread overview: 14+ messages / expand[flat|nested] mbox.gz Atom feed top
2006-08-09 8:38 [PATCH 1/6] ehea: interface to network stack Jan-Bernd Themann
2006-08-09 9:08 ` Christian Borntraeger
2006-08-11 11:02 ` Jan-Bernd Themann
2006-08-09 13:06 ` Alexey Dobriyan
2006-08-10 14:49 ` Jan-Bernd Themann
2006-08-10 6:15 ` Michael Ellerman
2006-08-10 7:30 ` Michael Ellerman
2006-08-10 14:28 ` Jan-Bernd Themann
2006-08-11 20:56 ` Anton Blanchard
2006-08-14 11:26 ` Jörn Engel [this message]
2006-08-14 14:38 ` Anton Blanchard
2006-08-14 15:43 ` Jan-Bernd Themann
2006-08-14 16:59 ` Arnd Bergmann
-- strict thread matches above, loose matches on Subject: below --
2006-06-21 12:40 Jan-Bernd Themann
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