Re: Framerate on iR...

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Don Hatch (hatch++at++hell.engr.sgi.com)
Fri, 5 Sep 1997 08:48:34 -0700

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On Sep 3, 3:12pm, Jan Barglowski wrote:
>
> I'm trying to optimize my framerate. At 30Hz PFPHASE_LOCK my app
> runs well, but about every 2 seconds the stats display "jumps"
> and I consistently get 2-4 misses shown in the stats window. For
> the app/cull/draw misses, there are zero misses shown.
>
> Now the fun part. I run the app at 60Hz PFPHASE_LOCK and I get
> the exact same symptoms: 2-4 misses and none shown for each of the
> processes. Thinking it was my program, I then ran "perfly esprit.flt"
> and got the same statistics.
>
> Setup: 12cpu iR, IRIX 6.2, Performer 2.1, running programs as root
> with non-degrading priorities and locked-down CPUs. My app can easily
> run 60Hz (well, I disabled preFrame() and postFrame() for these tests ;-)

Others have seen the every-two-seconds jump as well.
It turns out it was due to frame stats collection, which is done
be default every 2 seconds.

If you are working from perfly source,
you can change this by looking for the lines:
        pfFStatsAttr(fsp, PFFSTATS_UPDATE_SECS, 2.0f);
        first = 0;
and changing them to:
        pfFStatsAttr(fsp, PFFSTATS_UPDATE_SECS, whatever_you_want);
        if (i == ViewState->numChans-1)
            first = 0; /* did it on all the channels once */
(The added "if" should have been there all along;
without it, this will only happen on the first channel,
which is wrong when running with multiple channels;
this will be fixed in Performer 2.2).

Don

-- 
Don Hatch  hatch++at++sgi.com  (415) 933-5150  Silicon Graphics, Inc.
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