ZFS performance issues (solved?!)

Yarema yds at CoolRat.org
Mon Sep 1 16:32:07 UTC 2008

John Birrell wrote:
> For those people experiencing a performance degradation since the DTrace import,
> please update your copy of src/sys/cddl/compat/opensolaris/kern/opensolaris_kmem.c
> by either cvsup of direct edit to remove "#define KMEM_DEBUG".
> You only need to rebuild the opensolaris kernel module after this change. The code
> is shared between ZFS and DTrace via the opensolaris kernel module.
> This is also the reason why you found it necessary to add KDB, DDB and STACK to
> your kernel. After removing KMEM_DEBUG, you won't need those.
> Please confirm that this solves the problem you have been seeing.

Yes! Last night doing a csup would peg the Sys CPU usage at 100%.  After
rebuilding the opensolaris kernel module everything is back to normal.
There's a csup running as I type this and the system is upwards of 90%Idle.


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