On Mon, May 4, 2009 at 5:21 PM, Ron Foster at Baldor-IS <rfos...@baldor.com> wrote:
> I have been using the supplied example that had the minimum number of > CPUs set to 2. I don't think there is a real reason for having the minimum at 2. Earlier this week I raised the question "why would you ever set the minimum higher than 1" and the response was basically that some applications use the information about the number of CPUs. Those applications may get confused when you take away CPUs that they thought they would have. The other reason I see to do it is to prevent z/VM 5.4 share redistribution mess with your business objectives. Your under-utilized server will effectively take resources away from another busy server with the same importance for the business. > Now I am looking at our production SAP dialog servers. Each one has two > CPUs defined to it. This is because during some times of the month, at > some times of the day, one CPU cannot handle the load. Right. if your peak is more than one virtual CPU and you have enough CPU resources to spend on the workload, then you need more virtual CPUs. > Now I know that defining more CPUs than you need is not a good thing. > And most of the time, the nine servers that I am looking at only need > one CPU. I am wondering if anyone has seen any ill effects from > changing cpuplugd to allow the minimun number of CPUs to be 1. I see cpuplugd mainly to have value when you run in LPAR and want L-shaped LPARs. With Linux on z/VM I do like the idea that reduced number of CPUs may improve chances of the virtual machine drop from queue nicely. But recent SAP releases have stuff that makes even the virtual 1-way stay in-queue, so there it does not help anymore. Rob -- Rob van der Heij Velocity Software http://www.velocitysoftware.com/ ---------------------------------------------------------------------- For LINUX-390 subscribe / signoff / archive access instructions, send email to lists...@vm.marist.edu with the message: INFO LINUX-390 or visit http://www.marist.edu/htbin/wlvindex?LINUX-390
