Re: Jobs using over 100% CPU

8.8.3 Why does my partition’s CPU utilization show a value greater than
100%?
Normally a partition’s CPU utilization ranges from 0% to 100%. There are
several reasons why the CPU utilization would be reported to be greater
than 100%:

If the partition is configured as shared and uncapped, the CPU utilization
can exceed 100%. The amount the partition can exceed 100% is dependent on
multiple settings including the number of physical and virtual processors,
the size of the shared processor pool, and the partition’s uncapped weight.

If performance data is refreshed rapidly, performance tools such as
WRKACTJOB may not have enough time to gather all the required counter
values and the resulting CPU utilization may inaccurate. As a result, CPU
can be incorrectly reported as more than 100%. To improve accuracy, allow
some time before refreshing the performance counters.

The IBM i operating system provides “helper threads” to assist with
functions such as database. If these helper threads consume considerable
CPU, there may be intervals in which the partition’s CPU utilization is
reported as greater than 100%.



*simple example:
CPU settings uncapped&shared:
1 Physical Processors
2 Virtual Processor
That would allow for 200% CPU in WRKACTJOB.


If you can call QLZARCAPI, you should be able to see the processor
settings.
The SQLSYSTEM_STATUS_INFO view
https://www.ibm.com/docs/en/i/7.4?topic=services-system-status-info-view

Provides similar information.



Reference:
IBM i on Power - Performance FAQ April 23, 2021
https://www.ibm.com/downloads/cas/QWXA9XKN


Bryan

On May 18, 2021, at 4:49 AM, Jack Kingsley <iseriesflorida@xxxxxxxxx>

wrote:

Brad, if there was not an issue with the list jobs api, do these jobs

work

as normal then. What is the reason for the list jobs api issue, PTF's or
?? This issue isn't related to so many jobs on the system that the api
doesn't work well building the list.

On Mon, May 17, 2021 at 10:46 PM Vern Hamberg <vhamberg@xxxxxxxxxxxxxxx>
wrote:

Jim, I think I heard, and you seem to say, that each core - is that the
right unit - gives 100%, so 2 of them give a total of 200%? I just read
something that said if 3 cores are each at 60%, the reported percentage
would be 180%? It seems this multiple-core reporting is not unique to
the IBM i - it applies to laptops, workstations - my laptop has 2 cores,
4 logical processors (this doesn't matter, right?). Although the
performance tab of Task Manager looks like it has a max of 100%, I've
seen more than that there.

Regards
Vern

On 5/17/2021 6:55 PM, Jim Oberholtzer wrote:

It’s not overclocking. The partition is set up uncapped, so it will

use as much CPU as it can, unless the other partitions are asking for

their

share.

They did you a huge favor setting it up that way. I’d let it be…

Jim Oberholtzer
Agile Technology Architects

On May 17, 2021, at 6:52 PM, Brad Stone <bvstone@xxxxxxxxx> wrote:

I just ask. It's a 15 partition hosted system. They only use one
partition.

Is there some maths to do in the calculation when working with

multiple

LPAR systems when we see over 100%? 900% seems like some serious
overclocking. :)

On Mon, May 17, 2021 at 4:31 PM Jon Paris <jon.paris@xxxxxxxxxxxxxx>

wrote:

How many partitions on the box Brad. This happens quite often for us

when

we run a CPU intensive process when no other partitions are in use.


Jon Paris

On May 17, 2021, at 5:10 PM, Brad Stone <bvstone@xxxxxxxxx> wrote:

I have a customer who is reporting that the CPU for some jobs is

over

100%

for a period of time.

WAS90SVR 875.39%
QINAVMNSRV 135%
QNPSERVS 900.28%

I'm guessing the first is a webserver job and the other two are

system

jobs, obviously.

It's only for a short time during the night that this seems to

happen.

All

other job CPUs (calculated using CPU time and elapsed time) show

exactly

the same as what shows on WRKACTJOB.

Of course, since this was at night they weren't able to compare

these

3

jobs on WRKACTJOB.

I know I've seen ++++ before for CPU percentage... but these seem

odd.

I do know that there seems to be issues with the list jobs API on

this

system to as it will return multiple instances of the same job from

time

to

time in the active job list (not using SQL, using the API).

Bradley V. Stone
www.bvstools.com
Native IBM i e-Mail solutions for Microsoft Office 365, Gmail, or

any

Cloud

Provider!
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