Thanks Adam, good book. Skimmed the chapters on CPU management and
dispatching processors to lpars. Got it bookmarked, and will spend more
time reading soon. Thanks again.
--Dave Day
----- Original Message -----
From: "Gerhard Adam" <[EMAIL PROTECTED]>
Newsgroups: bit.listserv.ibm-main
To: <[email protected]>
Sent: Sunday, January 21, 2007 8:01 PM
Subject: Re: LPAR's and CPU's
All of the recent posts regarding LPAR's and their CPU utilization
prompts a couple of questions on my part. 1)Does anyone know the
mechanism
used to distribute CPU's to LPARS while they are >running? Another way
of
stating this question is what happens to the executing TCB or SRB on a
given processor in LPAR A when the code in charge of distributing CPU
resources decides LPAR A >has consumed enough, and LPAR B should now get
the processor? I would assume it forces some interrupt on the processor,
probably a CPU timer, but am curios if this is correct? 2)Is there any
>accounting for this loss of processor availability within MVS? The MVS
dipatcher running in an LPAR that had n+ processors to use, and now has
n,
how does it get notified it has one or more less >processors to use, and
then at a later time, one or more additional to dispatch on? I've
searched IBM's web site for doc and can't find anything. If there's a
redbook out there that talks about this, I'd >appreciate a link to it.
1. Nothing in particular happens to the TCB/SRB since z/OS doesn't know
about it. The loss of actual computing power is conveyed by a lower SRM
constant as the number of engines increases.
2. When a reduction or increase in processors is relayed to z/OS by
configuring processors on or offline. (Either by operator action or IRD)
3. If an operator configures a processor on or offline, the SRM constant
is
recalculated. This is NOT done when the processors are brought on or
offline by IRD.
4. Good documentation on this is in the Redbook "Intelligent Resource
Director".
Hope this helps
Adam
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