"High" cpu usage when using ZFS cache device

[Ivan Voras]

On 11/16/10 08:16, Christer Solskogen wrote:
> On Tue, Nov 16, 2010 at 1:30 AM, Brian Reichert<reichert at numachi.com>  wrote:
>> On Mon, Nov 15, 2010 at 09:50:50PM +0100, Christer Solskogen wrote:
>>> My load on my i7 920 is certainly higher when I add a 8GB usb stick as
>>> a ZFS cache device.
>>
>> USB 1.0?  2.0?  Dunno even if that would make a difference...
>
> This is USB 2.0. I didn't know USB had such much to say on the cpu.

You can easily test it - use the stick as a simple disk device with UFS 
and see how much CPU does it take simply to talk to the device.