The LPAR only has one logical CPU. So we can't do anything about that.

We'll have to see what we can do with the capacity. We don't need all that 
much. I am testing with SMAPI in the LPAR and it tends to take quite some CPU 
from time to time. Maybe it's better when we migrate into z/VM 7.1. I did apply 
a specific PTF for SMAPI in 6.4 but since we plan to migrate I don't want to 
install a new RSU in 6.4.

Met vriendelijke groet/With kind regards/Mit freundlichen Grüßen,
Berry van Sleeuwen
Flight Forum 3000 5657 EW Eindhoven

-----Original Message-----
From: CMSTSO Pipelines Discussion List <[email protected]> On Behalf 
Of Rob van der Heij
Sent: Friday, November 08, 2019 3:51 PM
To: [email protected]
Subject: Re: [CMS-PIPELINES] Trap error in stage STARMON

On Fri, 8 Nov 2019 at 12:59, van Sleeuwen, Berry <[email protected]>
wrote:

> Well, the affected LPAR is capped at 6% CPU. And as it turns out a
> SMAPI process is active at 5% for one or two minutes, and just in that
> minute the MONWRITE machine might have had just a fraction too little
> CPU time. Oddly enough we also have a reporting machine processing
> MONITOR records. Where MONWRITE simply writes selected records, the
> reporting machine has some serious plumbing but that machine had processed 
> all records within time.
> (as for CPU usage, MONWRITE uses 0.07% CPU and MONREPT 0.20%, both
> have a share ABS 3%.)
>

If you haven't yet, get the number of logical CPUs down. A problem with very 
"thin" CPUs is that z/VM is dispatching for a period in wall clock time, but 
when you're dispatched only 6% of the time, it's likely that your virtual 
machine gets empty time slices (the moment LPAR dispatches the logical CPU, the 
time slice has ended already). When that happens a few times, CP puts you in Q3 
and gives you larger empty time slices even less frequently. Your ABS 3% may 
not be worth a lot as that would be based on when all logical CPUs get 100% 
each. But at least you have the monitor data to figure it out.
I think z/OS recommends not to give a logical CPU less than 10% of a CPU worth 
of weight; such rules of thumb should resonate with your capacity planning 
friends as well.

Rob
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