Mark Lewis (markl++at++mistral.co.uk)
Tue, 29 Oct 1996 13:43:23 GMT
I'm trying to make some meaningful performance measurements on an
InfiniteReality.
I have successfully used the glInstrumentsSGIX calls to extract and display
some timing data from the pipes, but I now need to break it down to measure
the rendering times of individual channels within a pipe.
I understand that the glFlushRasterSGIX call can be made in order to make a
measurement which corresponds to the time at which all preceeding GL
commands have been rasterized (that is - written to the frame buffer). So I
could make a glFlushRasterSGIX call between each channel just before I
measure the end time with glReadInstrumentsSGIX.
The problem is that the act of flushing the pipeline in order to measure the
correct time is surely going to cause a loss of performance because of the
time wasted in the GE(s) while the RM(s) are finishing thier work.
My questions, therefore, are:
1. Can someone please confirm or deny the above.
2. Assuming that I am correct, is there a way of measuring the time
taken to render each channel, without adversely affecting the
machine's performance ?
Many thanks, in advance.
Mark Lewis
Principal Development Engineer
Equipe Electronics
13 Liverpool Gardens
Worthing
West Sussex
England
BN11 1RY
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