On Thu, Aug 20, 2009 at 1:27 PM, Michael Coffin<michaelcof...@mccci.com> wrote:
> PS: Yes, we've given each Linux server 5 virtual CPU's, which map to > two real IFLs. Our thinking on this is that the Linux guest "should" > dispatch more work simultaneously with 5 CPU's (and the two real IFLs > can more than handle the load). Comments? Good idea/bad idea? Pretty bad idea. Increases cost and makes performance worse. You never need more virtual CPUs than you have real ones. http://nl.wikipedia.org/wiki/Stoelendans But even that number is for most systems too much and useless as rule of thumb. Your Linux server needs one virtual CPU to run. You add another one only if all following are true: - your workload can use multiple CPUs (not every workload can) - business justifies that it uses that amount of resources (in your case, that one guest uses more than half of your CPU resources on its own) - total utilization is low enough that there is a reasonable chance it would get more than one full engine when it wants Rob - "When you don't know, one will do. When you have measured, probably too." -- Rob van der Heij Velocity Software http://www.velocitysoftware.com/
