As Rob and Alan have less blatantly stated, Linux CPU numbers are bogus
in a virtual environment. The CPU reporting problem has been corrected
in ESALPS (now zVPS) for those that want to use linux numbers for
anything useful. If you don't have a mechanism to correlate the linux
cpu numbers to reality, then one would not want to take the "virtual
reality" too serious....
David Dean wrote:
On Thu, 12 Nov 2009 13:01:52 -0600, Alan Ackerman
<[email protected]> wrote:
Where are you getting the 99% number? Which version of Linux are you
running? Older versions of Linux were fooled by the CPU being taken away
and reported high values of CPU utilization in 'top' and elsewhere.
If all the numbers are from PerfKit, they don't make sense. You cannot
have 3 users running at 99% and have the 3 IFLs running at 10-15% each.
Are you sure you are looking at the same time interval? If you are looking
at both Linxu and VM tools, they may not match up.
Alan Ackerman
Alan (dot) Ackerman (at) Bank of America (dot) com
On Thu, 12 Nov 2009 13:17:26 -0500, Dean, David (I/S)
<[email protected]> wrote:
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
-----------------------------------------------------
Please see the following link for the BlueCross BlueShield of Tennessee E-
mail disclaimer: http://www.bcbst.com/email_disclaimer.shtm
========================================================================
