John:
Yes, I know the "problem" started with z/VM 5.1 (at 4.4 we didn't have this problem). But in answer to the original question: will utilizing the LPARs bring my performance back (or closer) to what it was?
David Wakser
InfoCrossing
________________________________
From: McKown, John [mailto:[EMAIL PROTECTED]]
Sent: Friday, July 28, 2006 11:57 AM
To: IBMVM@LISTSERV.UARK.EDU
Subject: Re: Performance under z/VM 5.1
I think I found the answer:
<quote>
Finally, zSeries hardware supports only up to two levels of SIE. When z/VM runs in basic mode (no LPARs), the first-level z/VM uses one level of SIE to dispatch its guests, leaving one level of SIE available for a second-level V=R or V=F z/VM to dispatch its guests. Thus VSE-on-VM-on-VM runs well (no performance impact) in basic mode when preferred guest support is used. This can only be done on a system prior to z/VM 5.1.0. However, when z/VM runs in an LPAR, the LPAR hypervisor uses one level of SIE to dispatch z/VM, and z/VM uses the second level of SIE to dispatch its guest. Thus VSE-on-VM-on-VM in an LPAR is a poor performer, because hardware support of SIE runs out after two levels. z/VM has to simulate the third level of SIE.
</quote>
From http://www.vm.ibm.com/perf/tips/z890.html
but this is talking about a z890, not a z800. It appears that a z800 can run in BASIC mode. But notice the sentence in red.
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