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    SubjectRe: Although CONFIG_IRQBALANCE is enabled IRQ's don't seem to be balanced very well
    On 1/10/06, Jesper Juhl <jesper.juhl@gmail.com> wrote:
    > On 1/10/06, Martin Bligh <mbligh@mbligh.org> wrote:
    > > Jesper Juhl wrote:
    > > > 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.
    > > >>

    What I have read is that first CPU is used more for interrupts to use
    the concept of maximizing cache locality. Probably kernel is
    optimizing this even with CONFIG option enabled.

    Nauman

    > > >
    > > >
    > > > 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?
    > >
    > > Is it HT? ISTR it was intelligent enough to ignore that. But you'd
    > > have to look at the code to be sure.
    > >
    > Dual Core Athlon 64 X2 4400+
    >
    > --
    > Jesper Juhl <jesper.juhl@gmail.com>
    > Don't top-post http://www.catb.org/~esr/jargon/html/T/top-post.html
    > Plain text mails only, please http://www.expita.com/nomime.html
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