RE: Re[4]: [GD-Windows] Performance timing

[Donavon K. <DKe...@io...>]

(To be more precise, it does a fixed-point multiply and shift to convert the
count to milliseconds.)

-----Original Message-----
From: Donavon Keithley 
Sent: Wednesday, February 11, 2004 11:02 AM
To: 'gam...@li...'
Subject: RE: Re[4]: [GD-Windows] Performance timing


GetTickCount is just a tiny function that reads a variable that's
incremented in the system timer interrupt handler.  In situations where this
timer is useful, the extra speed is insignificant.


-----Original Message-----
From: Carl Bevil [mailto:car...@ya...]
Sent: Tuesday, February 10, 2004 7:27 PM
To: Simon O'Connor
Subject: Re[4]: [GD-Windows] Performance timing


Did that, and they have a nice utility that performs some timing tests on
your machine and spits out a report (it's at
http://developer.nvidia.com/object/timer_function_performance.html).

The report had interesting results:

-----

QueryPerformanceFrequency() freq  = 0  2593560000 


method 0:
  QueryPerfCntr..()  10000 times
  tot:   0 6720740
  avg:   672.074000
  avg time:			 2.59132e-007


method 1:
  GetTickCount()  10000 times
  tot:   0 260708
  avg:   26.070800
  avg time:			 1.00521e-008


method 2:
  TimeGetTime()  10000 times
  tot:   0 1420712
  avg:   142.071200
  avg time:			 5.47785e-008



method 3:
  Pentium internal high-freq cntr()  10000 times
  tot:   0 840856
  avg:   84.085600
  avg time:			 3.24209e-008

-----

I've left out the data for less than 10,000 iterations for sake of length;
the averages were similar for these cases (and I ran the test a couple times
with similar results).

It looks like GetTickCount is the fastest, at least for this test setup on
my machine.  Am I reading the results wrong?  I would have expected RDTSC to
be the fastest.  What could this mean?  Is this because of the cache effects
that Jon mentioned?  Just curious.  :-)

Tbanks!

Carl


------------------------------------------
Tuesday, February 10, 2004, 4:44:01 PM, you wrote:


> Hi Carl,


> Have a search around nVidia's developer website
> (http://developer.nvidia.com), IIRC they did presentation surveying each
of
> the major timing methods with regard to using them to profile code and the
> advantages and disadvantages plus latencies of each.



-------------------------------------------------------
The SF.Net email is sponsored by EclipseCon 2004
Premiere Conference on Open Tools Development and Integration
See the breadth of Eclipse activity. February 3-5 in Anaheim, CA.
http://www.eclipsecon.org/osdn
_______________________________________________
Gamedevlists-windows mailing list
Gam...@li...
https://lists.sourceforge.net/lists/listinfo/gamedevlists-windows
Archives:
http://sourceforge.net/mailarchive/forum.php?forum_id=555