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    SubjectRe: SMP performance degradation with sysbench
    On Tue, Mar 13, 2007 at 09:06:14PM +1100, Nick Piggin wrote:
    > Well ignoring the HT issue, I was seeing lots of idle time simply
    > because userspace could not keep up enough load to the scheduler.
    > There simply were fewer runnable tasks than CPU cores.

    When you said idle I thought idle and not waiting for I/O. Waiting for
    I/O would be hardly a kernel issue ;). If they're not waiting for I/O
    and they're not scheduling in userland with nanosleep/pause, the cpu
    shouldn't go idle. Even if they're calling sched_yield in a loop the
    cpu should account for zero idle time as far as I can tell.
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