[fpc-pascal]Profiling and classes

[Preben Mikael Bohn]

Hi all, I am trying to write a basic object-oriented matrix library, but have
run into a problem.

I expected my OO routines to be somewhat slower than my equivalent non-OO
routines, which was also the case (the non-OO routines uses 10 sec for a
500x500 matrix inversion, while the OO routines uses 110 secs (!) for the
same).

To analyse where the problem is I have used the -pg option to make output for
use in the GNU profiler, gprof. In the non-OO program I get the following:

Each sample counts as 0.01 seconds.
  %   cumulative   self              self     total
 time   seconds   seconds    calls   s/call   s/call  name
 41.27      4.42     4.42      501     0.01     0.01  _FORWARDSUBS...
 30.44      7.68     3.26      501     0.01     0.01  _BACKWARDSUBS..
 28.20     10.70     3.02        2     1.51     1.51  _LUDECOMPOSITION$TAR
  0.09     10.71     0.01        1     0.01    10.71  program_init

As you can see the cumulative seconds are equal to the time I measured (using
"time" on the command line).

However when I run the OO program I get something like:

Each sample counts as 0.01 seconds.
  %   cumulative   self              self     total
 time   seconds   seconds    calls   s/call   s/call  name
 40.63     14.13    14.13 249874780     0.00     0.00  _SIMPLE..
[snip - a lot of lines]
  0.00     34.78     0.00        1     0.00    34.75  program_init

Here the cumulative seconds only shows 34.78 seconds, even though the output
from "time" gives 110 seconds...

Can anyone tell me what is going on? I guess it means that it uses a lot of
time (~70%) in some internal FPC routines I have no control over?

Best regards Preben

PS: It should be mentioned that in both cases the computer had nothing else to
do, and that the "time" command estimated the CPU usage to be 99%.