> > You used to be able to compile with -DVDBE_PROFILE=1 to enable some > > special assembly-language instructions that would use > hi-res timers on > > ix586 chips to provide the cycle counts needed to execute each > > instruction in a VDBE program. But I haven't used that feature in > > years so I don't know if it still works or not. > > If you are talking of the "rdtsc" instruction, then to work > with current dual core CPUs the test must be "pinned" to a > single CPU, or you could be reading TSC values from different CPU's. > > Other than that, as long as the code works on a "single-core" > CPU, it should work on newer ones. > > Off course, there is that word: "should" ;-) >
I would add that if using windows I recommend using QueryPerformanceCounter() instead of "rdtsc" as this function/call already handles the above mentioned issue which affects multiprocessor/multicore systems. In a previous job I did some performance metrics since I presumed it would be slow but remember being pleasantly surprised that it was as fast (circa 4 clock cycles to retrieve and store in integer) as using assembler code. This was using VS C++ 2003 compiler. I'm not aware of a similar call in Unix Regards Nick ******************************************************************** This email and any attachments are confidential to the intended recipient and may also be privileged. If you are not the intended recipient please delete it from your system and notify the sender. You should not copy it or use it for any purpose nor disclose or distribute its contents to any other person. ******************************************************************** ----------------------------------------------------------------------------- To unsubscribe, send email to [EMAIL PROTECTED] -----------------------------------------------------------------------------
