No, what I'm saying is this: If, for example, the virtual machine had a relative share of 3 assigned AND it had 5 vCPUs defined, each vCPU would get a relative share of 1 rather than 0.6 or 3/5 (share divided by number of vCPUs).
_____ From: The IBM z/VM Operating System [mailto:[EMAIL PROTECTED] On Behalf Of Stracka, James (GTI) Sent: Friday, March 23, 2007 3:19 PM To: IBMVM@LISTSERV.UARK.EDU Subject: Re: CPU usage -- virtual or dedicated ? So, you are saying that 5x1 does not equal 5? -----Original Message----- From: The IBM z/VM Operating System [mailto:[EMAIL PROTECTED] On Behalf Of Marty Zimelis Sent: Friday, March 23, 2007 3:16 PM To: IBMVM@LISTSERV.UARK.EDU Subject: Re: CPU usage -- virtual or dedicated ? You are misinterpreting the usage note. What it means is that relative shares are doled out as integers. In other words, while a virtual machine's relative share is normally divided equally amongst its vCPUs, when you get to the case where the number of those vCPUs exceeds the total relative share assigned to the user, each vCPU gets a minimum relative share of 1. Marty ____________________ Martin Zimelis Principal maz/Consultancy _____ From: The IBM z/VM Operating System [mailto:[EMAIL PROTECTED] On Behalf Of Stracka, James (GTI) Sent: Friday, March 23, 2007 3:06 PM To: IBMVM@LISTSERV.UARK.EDU Subject: Re: CPU usage -- virtual or dedicated ? That seems to be the opposite of what USAGE NOTE 6 states for HELP CPSE SHARE: "When setting SHARE RELATIVE on a userid that has multiple CPUs, the minimum share that the system will assign is one per virtual CPU. For example, if you SET SHARE MAINT RELATIVE 1 and MAINT has five virtual CPUs, the resulting SHARE will be set to five." By the above, setting RELATIVE 100 with 2 CPUs you get an effective RELATIVE 200. -----Original Message----- From: The IBM z/VM Operating System [mailto:[EMAIL PROTECTED] On Behalf Of Schuh, Richard Sent: Friday, March 23, 2007 2:59 PM To: IBMVM@LISTSERV.UARK.EDU Subject: Re: CPU usage -- virtual or dedicated ? 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 _____ If you are not an intended recipient of this e-mail, please notify the sender, delete it and do not read, act upon, print, disclose, copy, retain or redistribute it. Click <http://www.ml.com/email_terms/> here for important additional terms relating to this e-mail. http://www.ml.com/email_terms/ _____
