At 10:40 AM 6/11/2004 -0400, Mike Hornsby wrote:
>Below are two versions of the same COBOL Prime number program.
>The first version took 28,051 CPU Milliseconds, the final version took
>4,654 Milliseconds.
>Friday's trivia question is:  What changes resulted in the largest
>performance gains, and why?

The use of 'comp' in defining the variables in the compilation.  The reason
why is
without that, the default storage is 'character' or ASCII mode and the code
generated continuously converts the values from character to binary and
back when calculations are
performed using variables defined in this manner.  This makes the code path
quite a
bit longer with all the conversion steps involved, resulting in longer
execution times.



>
>Mike Hornsby Co-founder/Chief Technical Officer
>Beechglen Development Inc. (beechglen.com)
>513-922-0509 [log in to unmask]
>
>
>  00014          001000 IDENTIFICATION DIVISION.
>  00015          001100 PROGRAM-ID. PRIME.
>  00016          001200 DATA DIVISION.
>  00017          001300 WORKING-STORAGE SECTION.
>  00018          001400 01 PRIME-FLAG     PIC X .
>  00019          001500 01 CALC-NO        PIC 9(6) VALUE ZERO.
>  00020          001600 01 DIV-NO         PIC 9(6) VALUE ZERO.
>  00021          001700 01 R              PIC 9(9) VALUE ZERO.
>  00022          001800 01 N              PIC 9(9) VALUE ZERO.
>  00023          001900 01 PRIME-COUNT    PIC 9(5) VALUE 2.
>  00024          002000 01 RUN-TIME       PIC 9(9) COMP.
>  00025          002100
>  00026          002200 PROCEDURE DIVISION.
>  00027          002300 000-MAIN.
>  00028          002400   PERFORM 100-CHECK-NUM THRU 100-EXIT
>  00029          002500     VARYING CALC-NO FROM 3 BY 2
>  00030          002600     UNTIL CALC-NO > 10000.
>  00031          002700
>  00032          002800   DISPLAY 'PRIMES= ' PRIME-COUNT.
>  00033          002900     CALL INTRINSIC "PROCTIME" GIVING RUN-TIME.
>  00034          003000     DISPLAY 'TOTAL CPU MSECS=' RUN-TIME.
>  00035          003100   STOP RUN.
>  00036          003200
>  00037          003300 000-EXIT.
>  00038          003400
>  00039          003500 100-CHECK-NUM.
>  00040          003600      MOVE "Y" TO PRIME-FLAG
>  00041          003700      PERFORM 110-CALC-NUM THRU 110-EXIT
>  00042          003800       VARYING DIV-NO FROM 3 BY 1
>  00043          003900       UNTIL (DIV-NO > ((CALC-NO + 1) / 2)) OR
>  00044          004000       PRIME-FLAG = "N".
>  00045          004100       IF PRIME-FLAG = "Y" THEN
>  00046          004200          ADD +1 TO PRIME-COUNT.
>  00047          004300 100-EXIT. EXIT.
>  00048          004400
>  00049          004500 110-CALC-NUM.
>  00050          004600        DIVIDE CALC-NO BY DIV-NO GIVING N REMAINDER R.
>  00051          004700        IF R = 0 THEN MOVE 'N' TO PRIME-FLAG.
>  00052          004800 110-EXIT. EXIT.
>...
>PRIMES= 01230
>TOTAL CPU MSECS=000028051
>
>
>  00014          001000$CONTROL OPTIMIZE=1,SYNC32,POST85
>  00015          001100 IDENTIFICATION DIVISION.
>  00016          001200 PROGRAM-ID. PRIME.
>  00017          001300 DATA DIVISION.
>  00018          001400 WORKING-STORAGE SECTION.
>  00019          001500 01 PRIME-FLAG     PIC X .
>  00020          001600 01 CALC-NO        PIC 9(6) COMP VALUE ZERO.
>  00021          001700 01 DIV-NO         PIC 9(6) COMP VALUE ZERO.
>  00022          001800 01 R              PIC 9(9) COMP VALUE ZERO.
>  00023          001900 01 N              PIC 9(9) COMP VALUE ZERO.
>  00024          002000 01 PRIME-COUNT    PIC 9(5) COMP VALUE 2.
>  00025          002100 01 RUN-TIME       PIC 9(9) COMP.
>  00026          002200
>  00027          002300 PROCEDURE DIVISION.
>  00028          002400 000-MAIN.
>  00029          002500   PERFORM 100-CHECK-NUM THRU 100-EXIT
>  00030          002600     VARYING CALC-NO FROM 3 BY 2
>  00031          002700     UNTIL CALC-NO > 10000.
>  00032          002800
>  00033          002900   DISPLAY 'PRIMES= ' PRIME-COUNT.
>  00034          003000     CALL INTRINSIC "PROCTIME" GIVING RUN-TIME.
>  00035          003100     DISPLAY 'TOTAL CPU MSECS=' RUN-TIME.
>  00036          003200   STOP RUN.
>  00037          003300
>  00038          003400 000-EXIT.
>  00039          003500
>  00040          003600 100-CHECK-NUM.
>  00041          003700      MOVE "Y" TO PRIME-FLAG
>  00042          003800      PERFORM 110-CALC-NUM THRU 110-EXIT
>  00043          003900       VARYING DIV-NO FROM 3 BY 1
>  00044          004000       UNTIL (DIV-NO > ((CALC-NO + 1) / 2)) OR
>  00045          004100       PRIME-FLAG = "N".
>  00046          004200       IF PRIME-FLAG = "Y" THEN
>  00047          004300          ADD +1 TO PRIME-COUNT.
>  00048          004400 100-EXIT. EXIT.
>  00049          004500
>  00050          004600 110-CALC-NUM.
>  00051          004700        COMPUTE R = FUNCTION REM(CALC-NO DIV-NO).
>  00052          004800        IF R = 0 THEN MOVE 'N' TO PRIME-FLAG.
>  00053          004900 110-EXIT. EXIT.
>...
>PRIMES= 01230
>TOTAL CPU MSECS=000004654
>
>
>
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