Thank you for the clarifications.
 
The VM LPAR in question is also running a z/OS guest hence the need to allocate 
the real CP's. From the HMC profile perspective, all the engines are 
shared among all the LPAR's.
 
Re John S.'s question, we used the VM performance toolkit to observe a 
WAS/Linux workload and could see the work only dispatching on the CP's.
 
I will report back when we get more info.
 
Thank you all for the assistance.
Edward Long

--- On Thu, 7/22/10, Alan Altmark <alan_altm...@us.ibm.com> wrote:


From: Alan Altmark <alan_altm...@us.ibm.com>
Subject: Re: IFL's, VM, and Linux
To: LINUX-390@VM.MARIST.EDU
Date: Thursday, July 22, 2010, 10:15 AM


On Wednesday, 07/21/2010 at 05:20 EDT, Ed Long <rdhm...@prodigy.net>
wrote:
> Thanks for thinking about our problem.
> So does your construct
>
> COMMAND DEFINE CPU 00 IFL
>
> effectively tell VM to assign the first real IFL to this VM as CPU 00?
On our
> system, the first real IFL is CPU 02 (00 and 01 are the CP's).

No.   A z/VM *mode* LPAR on a z10 or zEnterprise has separate pools of
CPs, IFLs, ICFs, zIIPs, and zAAPs at its disposal, depending on what's in
the LPAR activation profile.  By placing the "IFL" keyword on DEFINE CPU,
you tell CP to use a real IFL out of the pool when it dispatches the
guest.  The guest could be dispatched on any available IFL.

If you SET CPUAFFINITY OFF for the user (default is ON), all of the
virtual CPUs will be dispatched on the "primary" CPU type (CP's for a z/VM
mode LPAR).

And Ray is correct - in a z/VM mode LPAR you need COMMAND SET VCONFIG MODE
LINUX first.  Look at the table in the DEFINE CPU command.  (VCONFIG MODE
ESA/390 is the default for non-Linux-only LPARs.)

The relationship between the LPAR *mode*, as defined in the image profile
(ESA/390, Linux, z/VM), and the valid primary and secondary CPU types is
part of the machine architecture and is important to understand.  It can
seem a little strange until you realize that the purpose of this part of
the architecture is to ensure that an LPAR's CPU configuration (a) is
useful, (b) avoids abends, and (c) ensures workloads run on the CPUs they
are licensed for.  The SET VCONFIG command simulates the LPAR
configuration mode and so the virtual CPU configuration is dictated.

Alan Altmark
z/VM Development
IBM Endicott

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