The following is from the Performance Toolkit from z/VM 5.1. It shows a
difference between TCPU and VCPU as 3.66 seconds, which I assume is the CP
overhead. I watched this for a few minutes this morning and I can see the
difference stays between 3 and 4 seconds.
Userid %CPU TCPU VCPU Ratio Total DASD Avoid Diag98 UR Pg/s User Status
>System< 1.14 .681 .631 1.1 4.9 4.8 .0 .0 .0 .0 ---,---,---
ZOSONE 84.3 50.60 46.94 1.1 368 364 .0 .0 .0 .0 EME,CL3,DIS
ZOSTWO 4.49 2.695 2.561 1.1 3.7 3.3 .0 .0 .0 .0 EME,CL3,DIS
After I copied the above I did a IND USER ZOSONE and notice the difference
between VTIME and TTIME.
USERID=ZOSONE MACH=ESA STOR=1000M VIRT=V XSTORE=NONE
IPLSYS=DEV 0764 DEVNUM=00265
PAGES: RES=00255997 WS=00255997 LOCK=00000003 RESVD=00000000
NPREF=00000000 PREF=00000000 READS=00000001 WRITES=00002553
XSTORE=000003 READS=000071 WRITES=000074 MIGRATES=000000
CPU 00: CTIME=06:38 VTIME=088:05 TTIME=274:56 IO=296239
RDR=000000 PRT=006680 PCH=000000
Is VTIME the VM overhead in minutes and seconds? Is that included in TTIME?
If so the overhead of VM from the IND USER is over 30%. The ZOSONE machine was
last IPL'd (logged on) on Wednesday October 12th around 9 PM.
William L. Boyer
Senior IT Consultant / Senior Systems Programmer
Business and Technology Services
One West Pennsylvania Ave. ? Suite 700 ? Baltimore, MD 21204
Office: 410.832.8300 ext. 8419 ? Fax: 410.832.8329
www.emdeon.com/vips
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-----Original Message-----
From: VM/ESA and z/VM Discussions [mailto:[EMAIL PROTECTED] Behalf Of Bill
Bitner
Sent: Thursday, October 13, 2005 4:04 PM
To: [email protected]
Subject: Performance of zOS guest.
William Boyer <[EMAIL PROTECTED]> writes:
It really depends on the tools and which SMF records are used as to
the accuracy of the information.
>
>QUESTION: How much better would the zOS perform in it's own LPAR? =
>Currently we seem to be CPU constrained.
>Can we still share the zOS DASD back to zVM in READ mode on zVM?
It depends. If you look at the performance data from VM, most tools
report a total cpu for the guest and virtual cpu time (there are
places that virtual is called emulation tim). The difference between
the two values is CP time. A safe approximation is that when run in
an LPAR without VM, you'll save the CP time.
Bill Bitner - VM Performance Evaluation - IBM Endicott - 607-429-3286
