Re: dispatched cpu sharing/waiting ?

Are you by chance using iDoctor to see this "dispatched CPU
sharing/waiting" time?
Dispatched CPU waiting time means that the job has been dispatched to the
processor, but is not actually using CPU - it is time spent sharing the CPU
with other work. This is generally a normal type of wait since Power
processors have either 4 hardware threads (SMT4 with Power7) or 8 hardware
threads (SMT8 with Power8 and Power9). The CPU sharing/waiting time is due
to the HW SMT support.

The performance data investigator (PDI) does not show this level of
granularity - with PDI, you only see time dispatched to the CPU.

Are you seeing "CPU Queueing" time? CPU queueing is where the job is ready
to run, but the the processor is busy with other work and the job is
queued, waiting for the processor. This type of wait generally means you
need more CPU capacity (but not always....)

There are many reasons why a job could be running longer - you should look
at the job's "run/wait signature" to determine if there are other waits
that are causing delays in the job. If you have a baseline Collection
Services collection before the job started lagging, you could compare the
job's run/wait signature before the slowdown to see if there are any
significant differences.


Dawn

Dawn May Consulting, LLC

________________________________
From: MIDRANGE-L <midrange-l-bounces@xxxxxxxxxxxx> on behalf of
Steurbaut, Richard <rsteurbaut@xxxxxxxxxxxxxxxxxx>
Sent: Tuesday, July 24, 2018 1:00 PM
To: midrange-l@xxxxxxxxxxxx
Subject: dispatched cpu sharing/waiting ?

Hello, We have a job that is running longer and shows a good amount of time
being spent in dispatched cpu sharing/waiting. Would anyone be able to
explain what dispatched cpu sharing/waiting means. Thanks !
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