> -----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: [email protected]
> 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
