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JCL job using 34 ~ 45 % under CPU% factor
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sunny_io

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PostPosted: Mon Jun 14, 2010 7:19 pm    Post subject: JCL job using 34 ~ 45 % under CPU% factor
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Hi All.

The JCL I am running scans thru 2000 modules using a Rexx program I have written.
For scanning 200 modules , the Job ran in approximately 1 minute.

So expecting 10~12 mins run time for 2000 modules i ran the job but when i see the CPU % used by my job, it was flucntuating b/w 35 % to 45% ..

This I see when in spool i give DA on command line.

I first thought its the region parameter, had it as 5M so changed it to 256K .. but no effect.

Would appreciate inputs on what affects the CPU % which a job takes up..

My job :
000001 //SELEC JOB (XXXX,YYY,ZZZ)
000002 // CLASS=R, R=SHRT,P=
000003 // COND=(12,LE),
000004 // MSGCLASS=9,
000005 // NOTIFY=&SYSUID,
000006 // REGION=256K,
000007 // TIME=(1440),
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enrico-sorichetti

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PostPosted: Mon Jun 14, 2010 7:22 pm    Post subject: Reply to: JCL job using 34 ~ 45 % under CPU% factor
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i would check line 125 of Your rexx script, that' s where the cpu is looping
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expat

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PostPosted: Mon Jun 14, 2010 7:23 pm    Post subject:
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The quality of the code
What other jobs are processing to limit the amount of CPU available to you

Just a matter of curiosity - why did you reinvent the wheel when 3.13 works wonderfully well in 99% of cases.
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sunny_io

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PostPosted: Mon Jun 14, 2010 7:26 pm    Post subject: Re : enrico
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I don't think the Rexx program is looping as I did sample runs and Rexx is working fine..

I wanted to actually clarify that what determines that my job would get how much CPU % when there are many people running jobs with same priority as mine.

Understand that all would be interested to see the whole code before commenting .. but its just tooo huge..
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sunny_io

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PostPosted: Mon Jun 14, 2010 7:30 pm    Post subject: Re : All
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I had to find out in which all modules, initialization happens at item level in an cobol array ..
Example: following are some instances of initialization at item level..
Move SPACES to Z(1)
or Move SPACES to
XXXXXXXXX(YYYYYYYYYYYYYYYY)

Since 2 lines consequently could have initialization i had to try my hand on rexx. ( newbie to it )
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enrico-sorichetti

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PostPosted: Mon Jun 14, 2010 7:31 pm    Post subject: Reply to: JCL job using 34 ~ 45 % under CPU% factor
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what do You want form us!
You are telling that some process is using a certain % of CPU
OK! that' all we can say!

post useful info and You will get different replies
see
http://catb.org/~esr/faqs/smart-questions.html
on how to get the most when asking

Quote:
So expecting 10~12 mins run time for 2000 modules i ran the job but when i see the CPU % used by my job, it was flucntuating b/w 35 % to 45% ..

what relation do You expect it should exists between elapsed and CPU % ???
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sunny_io

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PostPosted: Mon Jun 14, 2010 7:31 pm    Post subject: Re : query
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Also , with so many people working simultaneously on our mainframe.. i don wanna be the one who takes away the max CPU time.. so how do i limit this 35 % to say like 5~10 % via JCL.. is there a way ?
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expat

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PostPosted: Mon Jun 14, 2010 7:33 pm    Post subject:
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But my question still remains. Why did you waste however long it took you to write the REXX code when 3.13 would have done this for you, and is almost certainly less resource hungry than your home grown code.

Let's face it, what benefit do your employers get from you wasting time creating a far less efficient version of something that already exists and comes for free

Compare the usage of 3.13 in batch against your REXX.
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enrico-sorichetti

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PostPosted: Mon Jun 14, 2010 7:37 pm    Post subject: Reply to: JCL job using 34 ~ 45 % under CPU% factor
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Quote:
Also , with so many people working simultaneously on our mainframe.. i don wanna be the one who takes away the max CPU time.. so how do i limit this 35 % to say like 5~10 % via JCL.. is there a way ?


don' You thing than WLM or even the older SRM might be smarter than You in balancing the workload

if Your job uses a certain amount of CPU is because the powers of zOS decided that it is safe

topic going down the sink going to be deleted shortly
today is not psychic day, is get rid of useless topic day
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Robert Sample

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PostPosted: Mon Jun 14, 2010 7:37 pm    Post subject:
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Quote:
I first thought its the region parameter, had it as 5M so changed it to 256K .. but no effect.
My first thought ... WHY ON EARTH WOULD YOU THINK REGION SIZE WOULD AFFECT CPU USAGE??????

There are some cases where reducing the region size could impact CPU usage -- but mostly it would make CPU usage go up as thrashing started and page counts went through the roof. This is much like burning down your house to get rid of termites -- yeah, the termites are gone but now you've got worse problems.

CPU consumption is based upon the work done by the program -- not the region size, not the number of data sets, not even where the data sets are located.
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sunny_io

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PostPosted: Mon Jun 14, 2010 7:39 pm    Post subject: Re : Expat
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3.13 as i know is to compare 2 datasets.

Consider the following scenario pls :
Module 1:
Move Zero to Array1(index1)
Module 2:
Move Zeroes to
Array 2 ( index 4 )
Module 3:
Move Spaces to Array 3 ( 2)

All of the above modules qualify my requirement since in them there is item level initialization for some array .. doesn't matter which array..

In end -> we have to find a number -> how many modules have item level initilizations for Arrays out of the 2000 modules ?

Would 3.13 help with this.

TIA
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sunny_io

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PostPosted: Mon Jun 14, 2010 7:42 pm    Post subject: Re : All
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Well, why I was anxious about the CPU usage high was in recent past,
for our team members , jobs were not running as a oarticulat job was taking 78% CPU % ... so it was shared that since tat job is taking all the resources , others are not getting any CPU usage..
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expat

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PostPosted: Mon Jun 14, 2010 7:42 pm    Post subject: Re: Re : Expat
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sunny_io wrote:
Would 3.13 help with this.
Would I have suggested it for fun ?
That is exactly what 3.13 is for, finding things in datasets and PDS's
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sunny_io

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PostPosted: Mon Jun 14, 2010 7:43 pm    Post subject:
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Robert Sample : WHY I THOUGHT SO --> cause I am new and wasn't tought the basics and was directly in a customized project.. didn't get to learn the basics..
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expat

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PostPosted: Mon Jun 14, 2010 7:45 pm    Post subject:
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Quote:
job was taking 78% CPU %
The mind boggles icon_rolleyes.gif
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sunny_io

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PostPosted: Mon Jun 14, 2010 7:47 pm    Post subject:
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Expat - and is 3.13 flexible enough for the following scenario also ?

028900 MOVE ZEROES TO D00071-TB-1ST-DG-SUB
029000 (D00071-TB-IDX)

now the initialization is in 2 lines since the Array name D00071-TB-1ST-DG-SUB is too big ... so index is in next line..

My search is like :

Move ZEROES TO XYZ ( abc )

xyz CAN BE ANY combination of letters symbols and numbers
same goes for the index name..
and the statement can span in 2 lines...

What remains always in the statement is - MOVE , ZEROES/ZERO/ , ( , ) , TO

If yes, i'll go ahead , take a breakk and read about 3.13
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Robert Sample

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PostPosted: Mon Jun 14, 2010 7:51 pm    Post subject:
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Okay, now go learn about Workload Manager -- WLM -- (it's in the MVS bookshelf in the library at IBM's web site). If your job is running 35-40% of the CPU, it is because WLM has found that there is no workload with a higher priority requiring the CPU time. Of course, if you're running something like this as a production job, I'm sure someone at your site will set you straight before long.

And you need to be aware that computer work rarely scales up in a linear fashion -- if 200 members take 1 minute, it is not very likely that 2000 members will take 10 minutes. 20 to 40 minutes, I can see -- but not 10.
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enrico-sorichetti

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PostPosted: Mon Jun 14, 2010 7:52 pm    Post subject: Reply to: JCL job using 34 ~ 45 % under CPU% factor
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Your curiosity about zOS working can be easily satisfied by

http://publibz.boulder.ibm.com/zoslib/pdf/zosbasic.pdf

or by he whole series of the ABC of ZOS system programming
search the forums or
http://www.redbooks.ibm.com/
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dneufarth

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PostPosted: Mon Jun 14, 2010 7:53 pm    Post subject:
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Enrico,

ROFLMAO unless you really have the code.
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enrico-sorichetti

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PostPosted: Mon Jun 14, 2010 7:55 pm    Post subject: Reply to: JCL job using 34 ~ 45 % under CPU% factor
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Quote:
If your job is running 35-40% of the CPU, it is because WLM


already expressed a similar concept,
we might have a case of split personality
the person who writes the questions is not the same person who reads the answers icon_evil.gif

but most probably the person who reads the answers does not exist icon_biggrin.gif
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