Messages in this thread | | | Date | Tue, 13 Mar 2007 11:31:34 +0100 | From | Andrea Arcangeli <> | Subject | Re: SMP performance degradation with sysbench |
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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. - To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
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