On Tue, May 27, 2008 at 3:33 PM, Ruslan Sivak russ@vshift.com wrote:

Akemi Yagi wrote:

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On Tue, May 27, 2008 at 1:07 PM, Tom Bishop bishoptf@gmail.com wrote:

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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

Thanks Tru and Johnny, one more question. Can I just use the centos5-testing repo, ie, yum enablerepoxxx install kernel-vm? I ask because I tried and while it worked it loaded an older kernel. Should I just go to tru's directory and install the RPM directly? Also, ok more than one question, are the open-vm-tools in the same repo or only found in Johnny's testing directory. Thanks again...

On Tue, May 27, 2008 at 8:59 PM, Les Mikesell lesmikesell@gmail.com wrote:

Ruslan Sivak wrote:

...

...

...

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?

It depends on the host hardware and OS - many combinations have trouble servicing the 1000hz guest clock which has to be simulated in software. Also, some host systems have variable speed CPUs controlled by power managment which throws off the guests:

http://kb.vmware.com/selfservice/microsites/search.do?language=en_US&cmd...

-- Les Mikesell lesmikesell@gmail.com

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CentOS mailing list CentOS@centos.org http://lists.centos.org/mailman/listinfo/centos

Thanks much, I have in the past compiled my own but thought I would check. A big THANKS to whoever provides them...

On Tue, May 27, 2008 at 3:17 PM, Akemi Yagi amyagi@gmail.com wrote:

On Tue, May 27, 2008 at 1:07 PM, Tom Bishop bishoptf@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 _______________________________________________ CentOS mailing list CentOS@centos.org http://lists.centos.org/mailman/listinfo/centos