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 14:17:30 -0400 [thread overview]
Message-ID: <3F8D8F3A.5040506@nortelnetworks.com> (raw)
In-Reply-To: Pine.LNX.4.56.0310151035480.2144@bigblue.dev.mdolabs.com
Davide Libenzi wrote:
> On Tue, 14 Oct 2003, Chris Friesen wrote:
>>I have a long-running cpu hog background task, and a high-priority
>>critical task that waits on a socket for network traffic. When a packet
>>comes in, I'd like the cpu hog to be swapped out ASAP, rather than
>>waiting for the end of the timeslice. Is there any way to make this happen?
> What do you mean for high priority? Is it an RT task? The wakeup (AKA
> inserion in the run queue) happen soon :
> IRQ->do_IRQ->softirq->net_rx_action->ip_rcv->...
> but if your task is not RT there no guarantee that it'll preempt the
> current running.
Yes, it was an RT task.
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.
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 18:17 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 [this message]
2003-10-15 18:35 ` Davide Libenzi
2003-10-15 20:13 ` Chris Friesen
2003-10-15 20:27 ` Andrew R. Reiter
2003-10-15 20:53 ` Chris Friesen
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