RE: Anyone every seen a VM image run in slow motion?

The core issue has to do with Linux's method for servicing clock interrupts, and how in VMWare environments, high CPU utilization can cause the interrupts to get delayed, and hence the clock to drift.

The separate issue is that under extremely high loads, VMs can become unresponsive, which will cause the machine to appear to hang. Good times.

The key is to look at which situation you're facing - if it's clock drift, you can use kernel parameters, vmware tools, etc. to deal with that.

If the VM is simply hanging for long stretches of time, you need to look at the overall load of the system.

Thanks,
Matt

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Matthew Zito
Chief Scientist
GridApp Systems
P: 646-452-4090
mzito_at_gridapp.com
http://www.gridapp.com

-----Original Message-----

From: oracle-l-bounce_at_freelists.org on behalf of Bobak, Mark Sent: Tue 9/29/2009 10:21 PM
To: post.ethan_at_gmail.com; oracle-l
Subject: RE: Anyone every seen a VM image run in slow motion?  

Hi Ethan,  

I've never heard of it, but Google for "linux vmware clock time skew" seems to yield a lot of hits.  

Hope that helps,  

-Mark

From: oracle-l-bounce_at_freelists.org [mailto:oracle-l-bounce_at_freelists.org] On Behalf Of Ethan Post Sent: Tuesday, September 29, 2009 10:14 PM To: oracle-l
Subject: Anyone every seen a VM image run in slow motion?  

Look at my watch...9:11 pm exactly.

hit return on "sleep 60"...

wait until it comes back, date on server says it took 60 seconds...

Look at my watch...now 9:12 and 14 seconds...huh, never seen that before.

This is VM ware by the way, Linux.

Just wondering if anyone here has seen anything like this. Hard one to Google as I can figure out exactly what terms I would use.

Thanks,
Ethan

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http://www.freelists.org/webpage/oracle-l Received on Tue Sep 29 2009 - 23:35:44 CDT