From: Chris Friesen <cfriesen@nortelnetworks.com>
To: Davide Libenzi <davidel@xmailserver.org>
Cc: Linux Kernel <linux-kernel@vger.kernel.org>
Subject: Re: question on incoming packets and scheduler
Date: Wed, 15 Oct 2003 16:13:31 -0400 [thread overview]
Message-ID: <3F8DAA6B.7060609@nortelnetworks.com> (raw)
In-Reply-To: Pine.LNX.4.56.0310151133030.2144@bigblue.dev.mdolabs.com
Davide Libenzi wrote:
> On Wed, 15 Oct 2003, Chris Friesen wrote:
>>It appears that 2.4.20 fixes this issue, but there is another one
>>remaining that the latency appears to be dependent on the number of
>>incoming packets. See thread "incoming packet latency in 2.4.[18-20]"
>>for details. This behaviour doesn't show up in 2.6, and I'm about to
>>test 2.4.22.
> Are you sure it's not a livelock issue during the burst?
I dunno, you tell me.
The test app simply sits in select() until a packet comes in, then it
spins on recvmsg() until there are no more messages. It uses
SO_TIMESTAMP to find out when the packet got to the kernel, and does a
gettimeofday() right after the recvmsg(), then calculates the delta for
each packet and the overall average.
With 2.4.[18-20], the overall average goes up when the number of packets
goes up. For 2.6.0-test6, it stays constant.
Chris
--
Chris Friesen | MailStop: 043/33/F10
Nortel Networks | work: (613) 765-0557
3500 Carling Avenue | fax: (613) 765-2986
Nepean, ON K2H 8E9 Canada | email: cfriesen@nortelnetworks.com
next prev parent reply other threads:[~2003-10-15 20:13 UTC|newest]
Thread overview: 8+ messages / expand[flat|nested] mbox.gz Atom feed top
2003-10-15 1:39 question on incoming packets and scheduler Chris Friesen
2003-10-15 3:42 ` Chris Friesen
2003-10-15 17:39 ` Davide Libenzi
2003-10-15 18:17 ` Chris Friesen
2003-10-15 18:35 ` Davide Libenzi
2003-10-15 20:13 ` Chris Friesen [this message]
2003-10-15 20:27 ` Andrew R. Reiter
2003-10-15 20:53 ` Chris Friesen
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