Strange systat output on SMP FreeBSD 5.0-Current

Petri Helenius pete at he.iki.fi
Thu May 15 23:35:03 PDT 2003


Dan Nelson wrote:

>per-cpu utilization should be even across all CPUs, since our
>schedulers do not do process affinity and are not HT-aware.
>
>  
>
That would be true if there would be no interrupts and no kernel time.
With them the system spends more time with one/some of the CPU's.
(or  systat lies, but I don't think so)

This is also why HT does not perform well if you have a lot of activity
that is behind an exclusive lock.

Pete




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