raid3 is slow

Pawel Jakub Dawidek pjd at
Thu Mar 29 16:18:24 UTC 2007

On Thu, Mar 29, 2007 at 10:58:22AM -0500, Eric Anderson wrote:
> On 03/29/07 10:52, Ivan Voras wrote:
> >Dag-Erling Sm?¸rgrav 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.

Maybe I missed it, but I think we should start from asking about CPU he
uses:) Full dmesg would be best.

Pawel Jakub Dawidek             
pjd at                 
FreeBSD committer                         Am I Evil? Yes, I Am!
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