[CentOS] Centosplus vmware kernels....???

[Akemi Yagi]

On Tue, May 27, 2008 at 3:33 PM, Ruslan Sivak <russ at vshift.com> wrote:
> Akemi Yagi wrote:
>>
>> On Tue, May 27, 2008 at 1:07 PM, Tom Bishop <bishoptf at gmail.com> wrote:
>>
>>> OK, so I need to bring up a new vm and was wondering what the state of vm
>>> kernels for centos. I have read this
>>> http://bugs.centos.org/view.php?id=2189
>>> about the tick divider but it wasn't clear what the best step forward is
>>> for
>>> centos 5.1 was, i usually ran with the clocksource=pit option and it
>>> looked
>>> like that and the divider option caused a problem.  I have in the past
>>> compiled my own but was wondering what others were now doing, thanks in
>>> advance 8-)
>>>
>>
>> Thanks to Tru, kernel-vm is all up-to-date and you can find it here:
>>
>> http://people.centos.org/tru/kernel-vm/
>>
>> and yes, using the clocksource=pit option should not be an issue with
>> these kernels.
>>
>> Akemi
>
> So if I understand this correctly, one should not be using a stock kernel
> when running inside a vm, but should use the kernel-vm kernel?
>
> Russ

You *can* run the distro kernel inside a vm.  The CentOS bug entry
referred to by the original poster explains in great details why a
kernel with 100hz clock rate (kernel-vm) gives you improved
performance compared to the distro standard kernel (1000hz) and
handles clock drifts better.  Recent distro kernels offer a new kernel
option "divider=" that lets you reduce the clock rate.  This should
eventually eliminate the need for the kernel-vm.  However, at the
moment, the divider= option has a bug that causes problems when it is
combined with clocksource=pit.  And the timer "pit" is often used when
the system clock tends to go faster.

Akemi