From: Davide Libenzi <davidel@xmailserver.org>
To: Chris Friesen <cfriesen@nortelnetworks.com>
Cc: Linux Kernel <linux-kernel@vger.kernel.org>
Subject: Re: question on incoming packets and scheduler
Date: Wed, 15 Oct 2003 11:35:07 -0700 (PDT) [thread overview]
Message-ID: <Pine.LNX.4.56.0310151133030.2144@bigblue.dev.mdolabs.com> (raw)
In-Reply-To: <3F8D8F3A.5040506@nortelnetworks.com>
On Wed, 15 Oct 2003, Chris Friesen wrote:
> 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.
Are you sure it's not a livelock issue during the burst?
- Davide
next prev parent reply other threads:[~2003-10-15 18:41 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 [this message]
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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