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    SubjectCONFIG_IRQBALANCE for 64-bit x86 ?
    On 32-bit x86, we have CONFIG_IRQBALANCE available,
    but not on 64-bit x86. Why not?

    I ask, because this feature seems almost essential to obtaining
    reasonable latencies during heavy I/O with fast devices.

    My 32-bit Core2Duo MythTV box drops audio frames without it,
    but works perfectly *with* IRQBALANCE.

    My QuadCore box works very well in 32-bit mode with IRQBALANCE,
    but responsiveness sucks bigtime when run in 64-bit mode (no IRQBALANCE)
    during periods of multiple heavy I/O streams (USB flash drives).

    That's with both the 32 and 64 bit versions of Kubuntu Gutsy,
    so the software uses pretty much identical versions either way.

    As near as I can tell, when IRQBALANCE is not configured,
    all I/O device interrupts go to CPU#0.

    I don't think our CPU scheduler takes that into account when assigning
    tasks to CPUs, so anything sent to CPU0 runs with very high latencies.

    Or something like that.

    Why no IRQ_BALANCE in 64-bit mode ?
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      Last update: 2007-11-20 05:15    [W:0.037 / U:30.904 seconds]
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