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Date: Mon, 01 Sep 2008 12:32:04 -0400
From: Yarema <yds@CoolRat.org>
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To: John Birrell <jb@what-creek.com>
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Cc: stable@freebsd.org
Subject: Re: ZFS performance issues (solved?!)
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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.

Thanks,
Yarema