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    SubjectRe: Bad network performance over 2Gbps
    On Wed, Apr 16, 2008 at 01:36:36AM +0300, Anton Titov wrote:
    > On Tue, 2008-04-15 at 13:40 -0700, Kok, Auke wrote:
    > > Willy Tarreau wrote:
    > > 1) turn the in-kernel IRQBALANCE option off !
    > Actually it may be already removed. I remember it being under "Processor
    > type and features" and I currently cannot find it there for x86_64
    >
    > > 2) use either the userspace `irqbalance` daemon or
    > > 3) set smp_affinity manually
    >
    > I tried echoing 3 (assuming that CPU0 and CPU1 will share their cache,
    > as advised in other mails) into smp_affinity of all ethX interrupts and
    > no positive result was observed.

    But have you disabled irqbalance before doing this ? (you must reboot
    and pass "noirqbalance" on the command line for this).

    Also, if you are running on quad-core intel CPUs, I'm told that they're
    simply two standard dual-core CPUs in the same case, so there is no
    shared cache between any core. You should try to assign all irqs to
    CPU0 for a test. It *must* make a difference, in either direction.

    > I will try disabling NAPI and limiting e1000 interrupts tomorrow.

    I found the parameter name I was speaking about : InterruptThrottleRate.
    Beware it's an array with one entry per NIC, so you have to set as many
    values as you have NICs. I have always observed huge performance boosts
    when using the tunables the driver provides.

    Willy



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