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Message-ID: <9a8748490601101410i31a8447ev2bf8fafe570fc407@mail.gmail.com>
Date: Tue, 10 Jan 2006 23:10:22 +0100
From: Jesper Juhl <jesper.juhl@gmail.com>
To: Martin Bligh <mbligh@mbligh.org>
Subject: Re: Although CONFIG_IRQBALANCE is enabled IRQ's don't seem to be balanced very well
Cc: Josef Sipek <jsipek@fsl.cs.sunysb.edu>,
       Linux Kernel Mailing List <linux-kernel@vger.kernel.org>
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On 1/10/06, Martin Bligh <mbligh@mbligh.org> wrote:
> Josef Sipek wrote:
> > On Tue, Jan 10, 2006 at 12:14:42PM +0100, Jesper Juhl wrote:
> >
> >>Do I need any userspace tools in addition to CONFIG_IRQBALANCE?
> >
> >
> > Last I checked, yes you do need "irqbalance" (at least that's what
> > the package is called in debian.
>
> Nope - you need the kernel option turned on OR the userspace daemon,
> not both.
>
Ok, good to know.

> If you're not generating interrupts at a high enough rate, it won't
> rotate. That's deliberate.
>

Hmm, and what would count as "a high enough rate"?

I just did a small test with thousands of  ping -f's through my NIC
while at the same time giving the disk a good workout with tons of
find's, sync's & updatedb's - that sure did drive up the number of
interrupts and my load average went sky high (amazingly the box was
still fairly responsive):

root@dragon:/home/juhl# uptime
 22:59:58 up 12:43,  1 user,  load average: 1015.48, 715.93, 429.07

but, not a single interrupt was handled by CPU1, they all went to CPU0.

Do you have a good way to drive up the nr of interrupts above the
treshhold for balancing?

--
Jesper Juhl <jesper.juhl@gmail.com>
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