Unresponsive after dtrace

[Wes Morgan]

On Mon, 1 Sep 2008, John Birrell wrote:

> On Sun, Aug 31, 2008 at 06:35:16AM -0500, Wes Morgan wrote:
>> I know this has been reported already, but I want to give a "me too".
>> After installing a new world and kernel from the tree yesterday afternoon,
>> I let my system run all night. This morning everything was extremely
>> sluggish and unresponsive. According to top, which I thankfully left
>> running, processes were going in and out of "*kmem_" (obviously
>> truncated). CPU usage was 80+% system and load averages were around 5.4.
>> The only changes I made to my system besides upgrading were to include the
>> options KDB, DDB and STACK in my kernel for zfs functionality.
>> Unfortunately, I cannot try without those options since my root is zfs.
>> Booting a kernel from 8/20 works fine.
>
> Wes, will you please try removing "#define KMEM_DEBUG" from:
>
> src/sys/cddl/compat/opensolaris/kern/opensolaris_kmem.c
>
> This is the likely cause of the performance problems you are seeing. It
> is also the reason why you needed to add DDB, DBB and stack to the kernel.
>
> The quickest way to try this is to just build the 'opensolaris' kernel module:
>
> (keep a copy of your current /boot/kernel)
> cd src/sys/modules/opensolaris
> make obj && make depend && make all && make install

Everything compiled with my original kern config (no STACK etc). I'll let 
it go for a bit and see, but I don't see any processes going into "kmem_" 
in top yet.