> -----Original Message----- > From: The IBM z/VM Operating System > [mailto:[EMAIL PROTECTED] On Behalf Of Scully, William P > Sent: Tuesday, September 26, 2006 3:25 PM > To: IBMVM@LISTSERV.UARK.EDU > Subject: Re: MIPS vs. Virtual CPUs > > Let me refine this question. > > - Two users. Similar workload. A real processor with multiple CPUs. > The underlying CP has no resource constraints. CP SHARE the same for > both users. The only "difference" is user A has one virtual processor > and user B has two virtual processors. > > I'm not really trying to solve a problem by asking this question. Just > trying to understand how CP tries to give everyone "their share". I > think we all expect that two users, over time, doing the same work, with > the same virtual machine settings, get about the same resources from CP. > I'm asking, does giving a user an extra virtual CPU imply that that user > is going to get more CPU cycles, merely because of the second virtual > CPU? > > I see Marty thinks the answer is no. That's my feeling too. Did this > change at z/VM vs. VM/ESA? Or was it always this way?
It has been this way since VM/XA. There have been many changes "around the edges" (e.g., Limit Shares), but the basic scheduling algorithm remains unchanged. And this is not a "feeling." This comes from reading the code. Marty