On Tue, Jun 14, 2011 at 7:57 PM, Scott Rohling <[email protected]> wrote:

> My statements were based on the help for CP SET SHARE..  my comments on math
> were somewhat tongue in cheek - but since this is a relative value - 100 is
> as good as any other to base things on..  set all your guests to 7 and use
> increment of 3 if you like.   No idea at all by what you mean by 'political'
> ..  and annoyed at the statement that the defaults are just flat out wrong.

My apologies. One should not post on the mailing list while standing
up or while in a hurry...

You can't do VM performance with just the CP help files. I provided
the link to the PDF that explains that it does not work the way you
might think it should. The reason you see relative share like 100 and
200 is not for simple math or aesthetics, but to compensate for the
fact that the allocated share is distributed over the virtual CPUs.
The paper explains what the implications are when you don't play the
game right.

We're pushing the scheduler to its limits with workloads that are
completely different from what it was designed for. It works as long
as you don't do silly things or try to mislead the scheduler.
Political tuning is when someone claims that VTAM is the most
important thing in the system and recommends it should have REL 10000
(or the z/OS sysprog insist that their OSA port should be "preferred
route" even though he has no clue...)

As for "wrong" - I thought that was beaten to death already. I buy an
adult beverage for the first* who can explain why it makes sense to
have the TCPIP stacks with a relative share 30 times higher than their
Linux production guests.

Rob
-- 
Rob van der Heij
Velocity Software
http://www.velocitysoftware.com/

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