raid3 is slow
Eric Anderson
anderson at freebsd.org
Thu Mar 29 15:58:32 UTC 2007
On 03/29/07 10:52, Ivan Voras wrote:
> Dag-Erling Smørgrav wrote:
>
>> You don't seem to understand what the load averages mean. They are
>> the average number of runnable threads in the scheduler queue over the
>> last one, five and fifteen seconds. Certain workloads will drive up
>> the load averages without consuming all available CPU time. This is
>> particularly the case for workloads where small chunks of data (e.g.
>> RAID3 stripes) are passed around between multiple threads.
>
> But, in his case the threads DO seem to consume much more CPU time than
> they should - especially the g_down thread. In this case, load avg ( as
> an approximation of real system load) is useful, and he's not concerned
> without cause.
>
>
It would be good to see output of a ps -auxl next time he's running the
test.
Eric
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