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43,50337/21/fqc.hlp
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FQC - MEASUREMENT AND TRACING SYSTEM FOR SIMULA PROGRAMS
========================================================
If a SIMULA program has been developed which will be used very often,
e.g. as a part in a regularly used production system, it is often
profitable to spend some efforts optimizing the program.
A central and sometimes non-trivial problem in program optimization
is to find the innermost loops of the program. Once the execution
profile of a program is known it is usually easy to make it faster
with a few changes such as modifications in processing algorithms or
by using a small machine language subroutine.
DEC-10 SIMULA is delivered with a frequency measurement system which
assists in spotting frequently executed parts of a SIMULA program.
The system consists of two SIMULA programs, FQCRED and FQCLST.
The system is used as follows:
The program to be analyzed must have been tested well enough to run
to normal completion. It is read by the program FQCRED which
produces two modified versions of it, one of which is a compilable
SIMULA program (.FQ1+.FQ2) and the other a listing later used to
produce the frequency listing (.FQD). The modified compilable
program is executed (.FQR) and produces, if normally terminated, a
file of measured frequencies (.FQS). This file is merged with the
listing output from FQCRED by the program FQCLST, which produces the
final output (.FQL).
The user may also measure the execution time for different parts of
his program by editing calls to a procedure Z_T(I) into his program.
A call with I > 0 initiates a timing which is ended by a call with
the corresponding negative I. The logic is as follows:
+100>=I>0 T0[I]:= cptime;
-100<=I<0 J:=-I; ACC[J]:= ACC[J]+(cptime-T0[J]);
Calls to Z_T may be overlapping (even partly).
For example:
BEGIN
....
Z_T(+1);------------+
.... |
Z_T(+2);---------+ |
.... | |
Z_T(+3);------+ | |
.... | | |
Z_T(-2);------)--+ |
.... | |
Z_T(-3);------+ |
.... |
Z_T(-1);------------+
....
END
The resulting CPU-times will be presented at the end of the result
file (.FQL). For reliable results, do not try to measure too small
intervalls (depending on the precision of the timing). Note that only
such measurements that yielded accumulated times > 0 will be printed.
The measured program should satisfy some restrictions:
i) The program must not contain the identifiers Z_Q, Z_T or Z__.
ii) The program should not use any files on DSK: named
<program name>.FQ1 .FQ2 .FQR .FQD .FQS .FQL or .FQT.
iii) The program should terminate through its last END.
I.e. not through call to Exit or through SIMDDT.
iv) The source code lines should preferably not contain
any internal TABs (leading TABs are OK). If so, the
produced frequency indicators (|) might be misplaced
(within such a line). TABs may be removed with
.COPY temp.sim=prog.sim(W).
Note that the frequency indicators will be positioned at the first
position of the symbol counted. Its related number should be
interpreted as the number of times this symbol has been PASSED during
the execution. An indicated label (L:) will thus tell how many times
control passed the label from left, excluding explicit jumps (GO TO
L).
By adding the switch /T to the filespecification requested by FQCRED
a trace file (.FQT) will be produced, containing the number of each
executed (counted) statement. This may be useful when debugging
Simulation programs or programs making use of resume/detach. If the
program terminates with an error the file with logical name TRACE
must be closed before leaving SIMDDT.
The result file (.FQL) will contain information about the number of
the first traced statement on each source line. Consequetive numbers
will be indicated as xx-yy in .FQT. Note that the file is created in
APPEND mode adding new traces to the end of the file. The trace file
will contain the first six characters of the traced symbol followed
by its statement number.
Adding a number to the trace switch (/T:x) will trace the executed
statements the first x times. Every statement number will be
displayed (no xx-yy compacting). X must be >= 0, /T:0 is equivalent
to /T.
The use of tracing will considerably increase the execution time of
the modified program. Thus it is not recommended to use timing (Z_T)
together with tracing. The tracing may be switched off by calling the
procedure TRACEOFF. It may be activated again by calling TRACEON.
If you want to include any of your external modules in the analysis,
run the program SIMEXP prior to FQCRED.
The following session illustrates the use of the system on the SIMULA
program FLOPY.SIM.
.run pub:fqcred
Welcome to FQCRED Version 3
Program:flopy
[FQCRED: CPU time: 0.88]
Running modified program: SIMULA: FLOPY
LINK: Loading
[LNKXCT FLOPY Execution]
If you want to have the result at once type .CONTINUE
To accumulate the frequencies just type: START
.con
Welcome to FQCLST Version 3
Result on file: DSK: FLOPY.FQL - Type CON to see them at once.
.con
Max --------------------- FQC Result ---------------------
BEGIN COMMENT FREQUENCY MEASUREMENT EXAMPLE;
INTEGER u,k; TEXT t;
z_t(+1);
1 |1
WHILE Draw(0.999,u) DO u:= u+2;
1636 |1 |1636
z_t(-1);
1 |1
z_t(+2);
1 |1
FOR u:= 1 STEP 1 UNTIL 5000 DO
1 |1
IF t = NOTEXT THEN k:=k+1;
5000 |5000 |5000
z_t(-2);
1 |1
z_t(+3);
1 |1
FOR u:= 1 STEP 1 UNTIL 5000 DO
1 |1
IF t == NOTEXT THEN k:=k+1;
5000 |5000 |5000
z_t(-3);
1 |1
z_t(+4);
1 |1
FOR u:= 1 STEP 1 UNTIL 5000 DO
1 |1
IF TRUE THEN k:=k+1;
5000 |5000 |5000
z_t(-4);
1 |1
END;
1 |1
FQC results:
Max frequency: 5000
Sum frequency: 31649
No. of executions: 1
CPU timing: Total 0.50 sec.
Call no. Time spent % of runtime
1 0.047 9.46
2 0.248 49.90
3 0.095 19.11
4 0.089 17.91
.DIRECT flopy
FLOPY SIM 1 <057> 8-Aug-78 User program
FLOPY FQ1 4 <057> 8-Aug-78 Modif. file part 1
FLOPY FQ2 3 <057> 8-Aug-78 Modif. file part 2
FLOPY FQD 1 <057> 8-Aug-78 Edited file with bars (|)
FLOPY FQR 11 <057> 8-Aug-78 REL-file from FQ1+FQ2
FLOPY FQS 1 <057> 8-Aug-78 Frequency + timing data (binary)
FLOPY FQL 3 <057> 8-Aug-78 Result file (FQS+FQD)
Cleaning up afterwards might be done with .DELETE *.FQ?
[End of FQC.HLP 78-08-16 MO]