Strange timing results

Alexandre Constantino alexandre.constantino at
Thu May 18 08:45:07 UTC 2006


I've obtained the strangest results on the tmtests (timing tests suites)
on an i386 (AMD XP 2,4 GHz) with a pc386 BSP.

For illustrations purposes, take the results for tm01:
NOTE: all times are in microseconds
rtems_semaphore_create                   926
rtems_semaphore_delete                   618
rtems_semaphore_obtain: available         92
rtems_semaphore_obtain: not available     92
rtems_semaphore_release                  180

I have tested tm01 to tm10 and the time disparity is of the same
magnitude. I have results from 2x to 15x higher than the ones mentioned
on the i386.pdf for a 16 Mhz CPU!

Any clue on what might be wrong?
Even stranger is the fact that the same executives where tested on bochs
(*) in the very same computer, and the time results were 4x to 2x
smaller than the ones i obtained while running the executives natively.
(*) with a "tunned" IPS and clock settings - since i was able to get
some "close" delay values

Thank you for your time.

Alexandre Constantino

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