Another thing I noticed is that this is one of those times when having 2
virtual cpus with 1 total physical cpu might have better performance than 1
full core, you might want to play with it. I've seen aix guys doing lots of
benchmarking to determine the sweet spot between virtual and physical cpus.

Roberto
On Sep 2, 2015 2:35 PM, <rob@xxxxxxxxx> wrote:

Thank you.

SELECT JBNAME, JBUSER, JBTHAC, JBTHCT
FROM qpfrdata.QAPMJOBMI
ORDER BY jbthct desc

Job Active Threads
Name user threads created
QSJSENDER ROB 1 440
HTTP QNOTES 259 266
HTTP QNOTES 260 264
DOTS QNOTES 214 225
DOTS QNOTES 215 223
QFFFFFA8A ROB 1 216
QSJHEARTBT ROB 1 215
PORT50410 MIMIXOWN 12 163

I was kind of thinking that one of these columns would top out at 8. But
I guess this is telling me that it is using a lot of threads, not how many
can be processed at once.

I read the suggested articles.

One article mentioned this: Retrieve Processor Multitasking Information
(QWCRTVPR) API. However they spelled the program wrong. This made it
very hard to find.
Kind of a stupid API. So, if I get zero on the parm does that mean:
A: The system may only use the primary thread but no additional threads.
B: The system may use the maximum number of threads that the hardware
supports.
Answer: Yes.
Question: No, wait, A or B?


So I guess this is telling us that "IF" we are using SMT then we're not
using 2 or 4; we're using 8. Just say 7 (primary plus 7 additional). I
think there's a long way to go to fill up this integer value. Also makes
it so some software vendor doesn't have to cross reference a table to see
how many the hardware supports (which is subject to change based on OS, TR
or PTF level).



Rob Berendt
--
IBM Certified System Administrator - IBM i 6.1
Group Dekko
Dept 1600
Mail to: 2505 Dekko Drive
Garrett, IN 46738
Ship to: Dock 108
6928N 400E
Kendallville, IN 46755
http://www.dekko.com





From: "Dawn May" <dmmay@xxxxxxxxxx>
To: Midrange Systems Technical Discussion <midrange-l@xxxxxxxxxxxx>
Date: 09/02/2015 11:53 AM
Subject: Re: SMT8
Sent by: "MIDRANGE-L" <midrange-l-bounces@xxxxxxxxxxxx>




Hi Rob,

Collection Services has information about all the threads that run for a
given job.
You can view this information using the Performance Data Investigator.
There are probably multiple ways to do this, but here's one way:

Start with Investigate Data -> Collection Services -> Job Statistics
Overviews -> Job Statistics by Job or Task.
This will display a table of data, one row for each job. Find the job you
are interested in and select it. (Search or filter the data in the table
-
don't try to scroll through it).
After you have selected the job, take "CPU Utilization for Jobs or Tasks"
as the "Select Action" drill down.
In the next chart, find the interval you are interested in (perhaps it is
one where you see the CPU Utilization peak for that job). Select be bar
for that interval by clicking on it.
That will cause the next chart to display information for that job for
just
that interval. If you don't select a specific interval, the drill down
will show a summary over the entire timeframe.

Take the "Select Action" drill down option of "CPU Utilization by Thread
or
Task" and this will display a list of threads for that job in order of
their CPU utilization.

(There might be an easier way to do this, but I don't have time to play
around much more today....)

The Collection Services QAPMJOBMI file contains information about every
thread, so you could query that file yourself.


The IBM i Performance FAQ has information on SMT modes - the different
levels supported by the various POWER hardware models and the associated
support in IBM i 7.1 and 7.2.
On POWER8, IBM i 7.1 defaults to SMT4 while IBM i 7.2 defaults to SMT8.

http://www-01.ibm.com/common/ssi/cgi-bin/ssialias?infotype=SA&subtype=WH&htmlfid=POW03102USEN



In addition, there is an excellent article on the developerWorks site on
IBM i 7.2 and POWER8 -

http://www.ibm.com/developerworks/ibmi/library/i-ibmi-7_2-and-ibm-power8/index.html



I hope you find these resources helpful.

Dawn May
www.ibmsystemsmag.com/Blogs/i-Can/



From: rob@xxxxxxxxx
To: Midrange Systems Technical Discussion
<midrange-l@xxxxxxxxxxxx>
Date: 09/02/2015 11:10 AM
Subject: Re: SMT8
Sent by: "MIDRANGE-L" <midrange-l-bounces@xxxxxxxxxxxx>



Is there some snapshot data I can query which I can sort by threads in use
by a particular job at that time?
I've seen a Domino compact go up to 3 threads by watching the job but I
wonder if the system is really using SMT8.


Rob Berendt
--
IBM Certified System Administrator - IBM i 6.1
Group Dekko
Dept 1600
Mail to: 2505 Dekko Drive
Garrett, IN 46738
Ship to: Dock 108
6928N 400E
Kendallville, IN 46755
http://www.dekko.com

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