Re: An observation on glxgears performance
Re: An observation on glxgears performance
- Subject: Re: An observation on glxgears performance
- From: Geoff Stahl <email@hidden>
- Date: Fri, 10 Jan 2003 16:32:28 -0800
This is a known issue that has been discussed a couple of times in
the last few days. When the window is in the foreground it is VBL
sync'd. This is being fixed on our end.
I just ran glxgears to see what my results are, and I find it
interesting. For the record, I've got a dual 1 gig g4 with a gig of
memory, a GeForce4 Ti graphics card, cinema display, and a CRT
monitor (an old Dell at 1024x768).
When I run glxgears, I'm seeing very unusual performance numbers.
For example, as I type in the mail app with glx fully visible on the
other edge of the cinema display it is running at ~60fps. There's a
several inch / several hundred pixel gap between the edge of the
mail app and the edge of the glxgears window.
If I move the mail app so that the right edge is just a few pixels
away from the left edge of glxgears I'm getting ~700fps. It's a real
interesting effect. Seemingly, the main focus window doesn't have to
be close, as long as some window of the focused app is close. In
other words, I can move the window where I'm composing this message
to my other display and glxgears continues doing close to 700ftp as
long as one of my mail windows is within a half dozen pixels or so
of the glxgears window.
This seems to be the case no matter what the focus window is -- a
carbon app, a cocoa app, an X11 app. Whatever app has focus, if the
edge of the app window is within a few pixels of the edge of
glxgers, glxgears just flys. If not, it slows to a crawl.
The disappointing thing is, if glxgears is the foreground app it
seems to be throttled back to 60fps. Though, if I drag it to my
second display it seems to max out at ~150 fps. And to continue the
oddness, if I move the foregound app (again, this mail window) next
to the glxgears window on the other app, glxgears reports ~600 fps
but it subjectively looks like about 2 (ie: it's very jerky).
So, I get wildly varying numbers that range from 60 fps to over 700
fps depending on what app has focus and where it is in relation to
the glxgears window.
--
Geoff Stahl
OpenGL Engineer
Apple
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