kern.hz = 10

[Ivan Voras]

2009/1/30 Julian Stecklina <js at alien8.de>:
> Mister Olli <mister.olli at googlemail.com> writes:
>
>> Hi,
>>
>> I've never experimented with the kern.hz variable, but on all
>> configuration examples for 8-CURRENT if always seen 'kern.hz=100'.
>>
>>>From where did you get your configuration?
>
> I use the default config (albeit renamed to BLITZXEN) from 8-CURRENT.

Due to bad performance of high HZ in VMs, in 8-CURRENT it is
explicitly reduced to 10 if the kernel is running under any kind of
virtual environment. This is a somewhat theoretical number and
probably needs tuning.

If you're interested in trying it out, you can increase it by adding
"kern.hz=xxx" to /boot/loader.conf and seeing what is the actual
performance influence of high HZ under Xen.