Some comments on ZFS

Gary Jennejohn garyj at
Mon Apr 16 11:46:32 UTC 2007

I wrote:
> With the old setup I saw:
> a) ``make -j2 buildworld'' usually pegged the CPU at 97%.
> With the new setup:
> a) ``make -j2 buildworld'' only reaches about 70% CPU load. Is ZFS stealing
>    so much CPU?

This turned out to be a problem with SCHED_ULE. I was seeing cpu0 80% idle
almost all the time. After switching to SCHED_4BSD I see both CPUs used
to within about 5% of each other. SCHED_4BSD tends to use cpu1 more than
cpu0. SCED_ULE exhibited the same behavior, but more dramatically.

Gary Jennejohn / garyjATjennejohnDOTorg gjATfreebsdDOTorg garyjATdenxDOTde

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