Bernard Leclerc (bleclerc++at++cae.ca)
Thu, 13 Jun 1996 14:28:20 -0400
> Subject: help on statistics interpretation
> I am having trouble interpreting some statistics information
> displayed by the Performer stats and would like to get some help in
> understanding the data. I am currently using Performer 2.0, IRIX 5.3
> on a 3 pipe ONYX.
>
> My questions are focused on the average frame time information and
> the missed frame information. I am getting information of the form:
>
> msec: Frame 70.2 app=13.2 cull=2.7 draw=6.9
> Frames 47 misses: total 13 app=0 cull=0 draw=0
>
> The program is running at 30 Hz LIMIT or LOCK, APP_CULL_DRAW mode.
As pointed out by another reader of this mailing list, there's been a
discussion on this matter a few weeks ago. If I recall corectly, Sharon Clay
mentionned there was a slight error in the Frame figure but the rest of the
stats were OK.
If I read it correctly, your application is running at 30 Hz, you have 3
processes (APP, CULL and DRAW) and the latency of this application is around 70
ms as reported by the stats.
Here, the latency is measured from the APP process until the image is
displayed. It means that a frame prepared by the APP will be rendered 70 ms
later after CULL and DRAW will be done with it.
If the stats were OK, the frame time should be 33.3 ms for APP + 33.3 ms for
CULL + 6.9 ms for DRAW (where the swapbuffer occurs). This would give us a
frame time of 73.5 ms but Performer reports 70.2 ! Where are the missing 3.3
ms?
I'd would appreciate if the Performer team could confirm/clarify my
interpretation of the stats.
--
Bernard Leclerc CAE Electronics Ltd., 8585 Cote De Liesse
Technical Leader Saint-Laurent, Quebec, Canada, H4L-4X4
3-D Graphics Applications tel: +1 514 341 2000 extension 2275
bleclerc++at++cae.ca fax: +1 514 340 5496
=======================================================================
List Archives, FAQ, FTP: http://www.sgi.com/Technology/Performer.html
Submissions: info-performer++at++sgi.com
Admin. requests: info-performer-request++at++sgi.com
This archive was generated by hypermail 2.0b2 on Mon Aug 10 1998 - 17:53:00 PDT