IBM Mainframe Forum

by **wicherc** » Thu Sep 06, 2012 7:34 pm

BillyBoyo: Thanks for your response. I never saw this format of coding. But i tested and work ok. But......
In our case, a program calls to a routine, for thousands, and in each call initialize an array with 4000 occurs. This method and others we tested, are consuming a lot of CPU in serv.units and cpu time (more than 10').
Thanks again!

by **dick scherrer** » Thu Sep 06, 2012 8:12 pm

Hello,

You might consider having an initialized set of data in the calling program, passing this as one of the parms in the CALL, and then the called code would spend NO time initializing . . . There would be 2 sets in the calling program.

One that is initialized and is never modified. The other would be simply moved to before the call.

by **BillyBoyo** » Thu Sep 06, 2012 8:14 pm

OK, time for you to look up "reference modification" in the Cobol manuals.

"Old style" would be slightly faster.

It's not clear to me if this has solved your problem. If not, describe your problem and someone can probably suggestion something.

by **dick scherrer** » Thu Sep 06, 2012 8:19 pm

Hello,

My guess is that if one move was issued in the calling program it would be far faster than any lines of individual code or INITIALIZE statements to initialize the the array in the sub-program.

If the goal is to reduce cpu time, reducing or eliminating code to "loop thru" will have the biggest impact.

by **wicherc** » Thu Sep 06, 2012 9:04 pm

Hi!
Thanks BillyBoyo and Dick.
The Dick's solution was one we tested, with some slight difference. Look at our code at the routine:

Select all

WORKING STORAGE
01 WCA-PRUEBA PIC 9(9) VALUE ZEROS.
01 TAB-INTERNA.
05 TAB-SDO OCCURS 4000 TIMES.
10 LIS-MTO-RDO-GR.
15 COD-CLI-CD PIC S9(9).
15 COD-CTA-CD PIC S9(9).
15 COD-TIP-DOC-CD PIC X(2).
15 NUM-DOC-NU PIC X(30).
--------- etc -----------------------------
01 MOV-INTERNA.
15 FILLER PIC S9(9).
15 FILLER PIC S9(9).
15 FILLER PIC X(2).
15 FILLER PIC X(30).
-------------- etc --------------------------
Both have the same qty of fields.

LINKAGE SECTION.
01 LLAMADA PIC X(7).
* ----------------------------------------
PROCEDURE DIVISION USING LLAMADA.
IF WCA-PRUEBA = ZERO
MOVE 999 TO WCA-PRUEBA
MOVE 'PRIMERA' TO LLAMADA
INITIALIZE TAB-INTERNA
MOVE TAB-INTERNA TO MOV-INTERNA
ELSE
MOVE 'RESTO' TO LLAMADA
MOVE MOV-INTERNA TO TAB-INTERNA.
GOBACK.

When the pgm calls to the routine for first time, find WCA-PRUEBA = 0, then took the INITIALIZE and move to the other set.
The difference with your suggestion was that the other set of data are inside the routine.
But . . . .
We test this option and compare with the original way and the results didn´t go the best:
Test 1 to 4: the original code with a sentence INITIALIZE TAB-INTERNA at each call. Test 5 to 8: the results testing with the code descripted before:

Select all

Test Elapsed Time CPU Time Serv. Units % WFL
1 1.50    0.58 14039k    66
2 1.70    0.59 14237k    38
3 0.50    0.50 12816k    97
4 2.10    0.74 18247k    30
5 8.2    1.25 30001k    20
6 1.7    1.22 29381k    68
7 1.4    1.21 29231k    95
8 1.6    1.21 29333k    74

The WFL values is an average we took from RMF for each test.
Thanks a lot for read from the beginning until here.

by **BillyBoyo** » Thu Sep 06, 2012 9:08 pm

In order of "performance"

MOVEing block which only ever holds initial values
The "offset move", "old school"
The "offset move", reference-modification
INITIALIZE
Any sort of loop

There will not be much to choose between the top four, but if doing it a lot of times, it'll add up.

The problem with the first three is ensuring that the data definitions always match when something changes.

This problem can be avoided through some "once-per-run" code in the program which checks that things match up.

by **wicherc** » Thu Sep 06, 2012 9:19 pm

One important clarification.
The code was tested 4 times each. The first four with the original code and with identical conditions, and the last with de code described.
This code is all the routine and was called 1 millon times in each time.

by **BillyBoyo** » Thu Sep 06, 2012 9:51 pm

Your results look "odd".

First thing is, are you sure they are the correct way around? I'll assume yes :-)

There is no way there should be twice as much CPU usage. Unless doing eveything twice, or the amount of extra you put in leads to the doubling. So, we have to see.

Firstly Did you check that after million calls LLAMADA is actually "RESTO"? If it is not, please show your compile options.

Secondly, change WCA-PRUEBA to PIC X. Put on an 88 "WCA-PRUEBA-FIRST-TIME VALUE ZERO." Add a 2nd 88 "WCA-PRUEBA-NOT-FIRST-TIME VALUE "1".

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IF WCA-PRUEBA-FIRST-TIME
SET WCA-PRUEBA-NOT-FIRST-TIME TO TRUE
INITIALIZE TAB-INTERNA
MOVE TAB-INTERNA TO MOV-INTERNA
MOVE 'PRIMERA' TO LLAMADA
ELSE
MOVE MOV-INTERNA TO TAB-INTERNA
MOVE 'RESTO' TO LLAMADA
END-IF

Just run once and post the results please.
Change TAB-INTERNA to PIC X(whatever) and get rid of all the subordinate items. They are not necessary, and just have to be maintained because they are there. Won't affect the run-time.

by **wicherc** » Thu Sep 06, 2012 11:08 pm

Yes, The first time LLAMADA is PRIMERA, and the 1MM with RESTO.
I´ll try with your suggest and post the results.
Thanks!

by **BillyBoyo** » Fri Sep 07, 2012 1:53 am

It's very strange. When I do a 20k MOVE to the table it blasts the INITIALIZE to pieces.

20K was just a guess, not knowing your actual length. I only had one field (4000 times) to INITIALIZE.

Even the extra code as you have it does nothing.

Yet you have it twice as slow.

What version of Cobol are you using (from the top of the compile listing)? Can you paste you compile options here, please?

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