David,
What kind of SHARE statements do you have in the Linux servers' directory
entries. That's what determines how much of the available CPU resource the
users get.
Marty
____________________
Martin Zimelis
Principal
maz/Consultancy
_____
From: The IBM z/VM Operating System [mailto:[email protected]] On
Behalf Of Dean, David (I/S)
Sent: Thursday, November 12, 2009 1:17 PM
To: [email protected]
Subject: zVM CPU allocation
OK, this is for all you guys that understand the magic tunnel in which CPU
processing (usage) flows from an IFL to a zLinux server.
We have a z10 running zVM 5.4 in a dedicated LPAR with 3 dedicated IFL's.
We have approximately 30 zLinux servers. Using IBM PerfKit, I list all of
the individual USER / zLinux CPU usages, each of which generally run in the
1 to 5 % range. These servers do of course peak higher but on average they
are pretty low. We then take a look at the 3 IFL's and see usage of maybe
5% on each. Now, let's say we have a USER / server or two or three go
berserk and peak CPU at 99 % for an extended period of time. We then look
at the IFL CPU usages and all three have climbed to maybe 10 to 15% each.
How did the CPU get allocated? Is it always spread evenly across the IFL's,
is that a setting? Why, if there were 3 USER / servers running at 99%, was
more CPU not allocated from the 3 IFL's? Why did the IFL's decide to
allocate X amount and go no further.
In the USER DIRECTORY I allocate storage but not CPU.
David M. Dean
Information Systems
BlueCross BlueShield Tennnessee
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