Unresponsive after dtrace

[Yarema]

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.

Same here.  Running root on ZFS.  Yesterday I hosed my system and
recovered by booting FreeSBIE, downloading the latest amd64-bootonly.iso
copying /boot/kernel/*, tweaking loader.conf for the GENERIC kernel and
I was back in business.  First thing was to csup again, add STACK to my
custom kernel (which is much like generic with all the drivers unrelated
to my hardware removed) and build/install world.  All looked good except
 running "systat -vmstat 1" shows Sys using 100% of CPU after a few
minutes.  I'm not even sure if it's related to anything specific running
on the box or not.  Just gets progressively more sluggish within minutes
of booting and all the cycles seem to be spinning in the Sys category
with almost nothing left for userland or anything else.  The network
stack seems to be routing traffic well enough though.  I can still
stream music and video and send emails such as this one routed via the
box in question.  But otherwise just about any load seems to send %Sys
into the stratosphere.

-- 
Yarema
http://yds.CoolRat.org/zfsboot.shtml