From: P@draigBrady.com
To: hadi@cyberus.ca
Cc: Karsten Desler <kdesler@soohrt.org>,
Robert Olsson <Robert.Olsson@data.slu.se>,
"David S. Miller" <davem@davemloft.net>,
netdev@oss.sgi.com, linux-kernel@vger.kernel.org
Subject: Re: _High_ CPU usage while routing (mostly) small UDP packets
Date: Tue, 07 Dec 2004 13:39:14 +0000 [thread overview]
Message-ID: <41B5B282.9040909@draigBrady.com> (raw)
In-Reply-To: <1102424673.1093.124.camel@jzny.localdomain>
jamal wrote:
> On Tue, 2004-12-07 at 07:50, Karsten Desler wrote:
>
>
>>Currently I'm having problems capturing packets with tcpdump (lots of
>>"packets dropped by kernel") which indicates to me that there's
>>genuinely not much (enough) idle time sitting around.
>>
>
> Ah, more hints. So you are not trying to forward - rather just packet
> capturing?
> Are you using a tcpdump patched with mmaped packet socket?
>
> The 230-240Kpps you are reporting as a capture dont seem as unreasonable
> as i thought then. Neither would the CPU use.
Yes this is vital Karsten, otherwise tcpdump
will do 2 syscalls per packet, which is the
bottleneck in my experience.
You may want to try a simpler capture program that
uses the kernel PACKET_MMAP feature directly:
http://www.scaramanga.co.uk/code-fu/lincap.c
--
Pádraig Brady - http://www.pixelbeat.org
--
next prev parent reply other threads:[~2004-12-07 13:39 UTC|newest]
Thread overview: 31+ messages / expand[flat|nested] mbox.gz Atom feed top
2004-12-06 20:53 _High_ CPU usage while routing (mostly) small UDP packets Karsten Desler
2004-12-06 21:48 ` David S. Miller
2004-12-06 22:41 ` Karsten Desler
2004-12-06 23:56 ` Con Kolivas
2004-12-07 0:18 ` Karsten Desler
[not found] ` <E1CbSf8-00047p-00@calista.eckenfels.6bone.ka-ip.net>
2004-12-07 0:20 ` Karsten Desler
2004-12-07 2:46 ` jamal
2004-12-07 2:54 ` Karsten Desler
2004-12-07 3:18 ` jamal
2004-12-07 3:24 ` Karsten Desler
2004-12-07 3:30 ` jamal
2004-12-07 4:02 ` Karsten Desler
2004-12-07 10:21 ` Karsten Desler
2004-12-07 12:34 ` jamal
2004-12-07 13:14 ` Karsten Desler
2004-12-07 10:47 ` P
2004-12-07 11:21 ` Karsten Desler
2004-12-07 12:38 ` Robert Olsson
2004-12-07 12:50 ` Karsten Desler
2004-12-07 13:04 ` jamal
2004-12-07 13:11 ` Karsten Desler
2004-12-07 13:39 ` P [this message]
2004-12-07 18:38 ` Karsten Desler
2004-12-08 5:39 ` Willy Tarreau
2004-12-08 13:08 ` Karsten Desler
2004-12-08 13:27 ` jamal
2004-12-07 21:10 ` Karsten Desler
2004-12-07 22:40 ` Robert Olsson
2004-12-08 22:06 ` Karsten Desler
2004-12-08 4:31 ` jamal
2004-12-08 13:26 ` Karsten Desler
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