The Relative 100 applies to the overall virtual machine. If you define each with 2 cpus, each cpu would be competing at a Relative 50 when the system is busy. That may be an inhibiting factor. With our TPF systems, each normally running with 3 CPUs - sometimes more, sometimes fewer, we multiply the number of cpus by 100 to arrive at a relative share value for the virtual machine. This seems to solve a lot of slowdown issues that our testers encounter.
Regards, Richard Schuh ________________________________ From: The IBM z/VM Operating System [mailto:[EMAIL PROTECTED] On Behalf Of Kris Buelens Sent: Friday, March 23, 2007 11:41 AM To: IBMVM@LISTSERV.UARK.EDU Subject: Re: CPU usage -- virtual or dedicated ? As the first share setting is "REL 100" they get the same priority as any other VM user that wants to run. So, if you want to give them a favor you should e.g. set the first share to REL 1000, or maybe ABS 30% 2007/3/23, Stracka, James (GTI) <[EMAIL PROTECTED]>: I am not in favor of dedicating virtual CPUs as this restricts the other users of the system and is a potential waste of resources and money. Since the CP Scheduler does an excellent job of distribution of the resources, then using the SHARE command might be better. Assuming there are more than two VSE machines of which two really need to use two virtual CPUs each and there are four real CPUs, then if I am correct issue two SET SHARE commands: set share vseguest1 relative 100 absolute 49% limithard set share vseguest2 relative 100 absolute 49% limithard Okay, it could be absolute 50% but if both VSE guests wanted the maximum resources at the same time, no other work would get done. My understanding of those two commands is that they would allow either VSE guest to get almost the full usage of two real CPUs each any time they need them. Stated another way, either could at most get 49% of the box leaving the remaining 51% for all the other users of the four CPUs. If both wanted the maximum at the same time it would be 49% for vseguest1, 49% for vseguest2 and 2% for the remaining users. Any other time, the workload would be spread evenly among all the guests in the box given QUICKDSP and other SHARE settings. Am I correct? -- Kris Buelens, IBM Belgium, VM customer support
