"High" cpu usage when using ZFS cache device

[Christer Solskogen]

On Tue, Nov 16, 2010 at 1:55 PM, Alexander Leidinger
<Alexander at leidinger.net> wrote:
> How do you measure that nothing is read or written to it?
>

I used zpool iostat -v

> Please check with
>  gstat -f '^<DEVICE>$'
> if there are really no reads/writes to the device (please replace <DEVICE>
> with the name of your USB device, e.g. da0).
>
> If you see writes, I would say
>  - this is the reason for the load
>  - your cache is on the way to be filled with
>   useful data
>

I see almost no writes (nor reads)

> If gstat shows zero activity, I suggest to run 'top -S' and look at the
> process(es) which consume about 10% CPU (do not take care about the idle
> process). Based upon this we can maybe suggest further things to
> investigate.
>

Heres the output of that:
CPU:  0.0% user,  0.0% nice, 11.8% system,  0.0% interrupt, 88.1% idle
Mem: 841M Active, 193M Inact, 5086M Wired, 4876K Cache, 1237M Buf, 5750M Free
Swap: 8192M Total, 8192M Free

  PID USERNAME    THR PRI NICE   SIZE    RES STATE   C   TIME   WCPU COMMAND
   11 root          8 171 ki31     0K   128K CPU0    0    ??? 713.62% idle
    5 root          5  -8    -     0K    76K zvol:i  5 401.9H 91.16% zfskern

Thanks for your time on looking into this :-)

-- 
chs,