You mentioned in another post that you are using Windows (version not
specified) and are using OpenMP with Visual Studio.
The safest way to do a scalability experiment is to change
the number of OpenMP threads. You'll need to set an environment
variable in the "Advanced system settings" of the "System" control
panel. Create a new (user or system) environment variable named
"OMP_NUM_THREADS" and give it a value (1, 2, 3, or 4).
Now, here's a little gotcha. The CodeAnalyst GUI only picks up the
environment variables when CodeAnalyst launches. So, when you go to
change the number of threads, you will need to exit CodeAnalyst,
change the value of the OMP_NUM_THREADS environment variable, then
launch CodeAnalyst again.
As a side note, CodeAnalyst is able to launch a BAT file that sets
environment variables and runs a workload. However, thread profiling
tracks the process running the BAT file (cmd.exe) instead of the workload.
Thus, the resulting thread chart is uninteresting. :-( I've passed this usage
issue on to the team.
Windows does provide a way to change the number of cores, but I do not
recommend fiddling with this setting. In all cases,
this requires a reboot and the confidence to change a system setting.
The method is different on different versions of Windows. On Vista, there
is a control panel which controls boot options. Follow Control Panel >
Administrative Tools > System Configuration and select the Boot tab in
the System Configuration dialog box. Click the Advanced options... button
and you will find a way to set the number of processors. On Windows XP,
you can run the System Configuration Utility by choosing Run... from the
Start menu and opening msconfig. Select the BOOT.INI tab and click the
Advanced Options... button. You will see an option to set /NUMPROC, which
is the number of processors at boot time. In any case, you'll need to
reboot. If you choose this method, you'll have to accept sole responsibility
for the results!
Take care -- pj
Hi, it's so difficult for me to understand all this. But wish you good luck.