Hi, Paul.
Ayer, Paul W wrote:
I am told (I'll have to get a copy of the vm profiles too)that for
now CPU 01 is the only CPU def in each of the Linux guest profiles.
And there is a dedicate statement too. So this leaves CPU 00 for VM.
The CPU definition statement in the CP user directory entry for each of
you Linux guests just tells CP that each Linux virtual machine has
available to it *1* (virtual) CPU, at virtual address x'01'. It doesn't
assign, even with the DEDICATE parameter of the CPU statement, a
particular real processor to each Linux guest.
so this was done by design for some reason.
This sounds like it was done by someone who did not fully understand
real vs virtual processors and how they are manged by CP. A virtual
machine can have:
1) more virtual process than there are real ones. (Although I generally
do not recommend such configurations unless there are some compelling
reasons for doing so....such as testing.)
2) the same number of virtual processors as real ones.
3) ewer virtual processors than real ones....but at least 1 virual CPU,
as not having any processors available at all makes running any o/s
rather diffiult....:-)
I'm thinking that this is a waste also. Just wanted to see if there
was some reason I had not heard of for this.
I would think it's a waste of time as well....I believe VM uses all of
the real processors it finds in it's LPAR all the time. I am unaware of
any facilities inside VM to tell it not to exploit one (or more) engines
in it's LPAR.
We really have four IFL's on that system with only two turned on
right now, but I'm starting to look at ramping things up some.
Good luck. Let us know how things turn out.
Thanks for the info,
Paul
-----Original Message----- From: Linux on 390 Port
[mailto:[EMAIL PROTECTED] On Behalf Of RPN01 Sent: Thursday,
March 06, 2008 4:13 PM To: LINUX-390@vm.marist.edu Subject: Re: vm
profile question
Z/VM's overhead is so little; I'd see no point in reserving an entire
engine
for it, unless you have a large CMS workload running beside your
Linux
guests. Even then, both the CMS guests and the Linux guests could
benefit
from the use of both CPUs when the load of one or the other exceeds a
single
CPU. I see no compelling benefit from such a segregation.
My question is, how has this segregation been implemented? This isn't
the
way the system runs by default, and would likely run better for
everyone
without the limitation.
--
Robert P. Nix Mayo Foundation .~.
RO-OE-5-55 200 First Street SW /V\
507-284-0844 Rochester, MN 55905 /( )\
----- ^^-^^
"In theory, theory and practice are the same, but
in practice, theory and practice are different."
On 3/6/08 3:00 PM, "Ayer, Paul W" <[EMAIL PROTECTED]> wrote:
We have two IFL's defined to one of our systems.
Today via the profiles we have it set so that CPU 00 is used by
only
VM,
and the Linux guests use only CPU 01 (really IFL's)
Does anyone else do this ... reserve a whole IFL for just VM?
Thanks,
Paul
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z/VM and mainframe Linux expertise, training,
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www.vsoft-software.com
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