Diagnosing first vs subsequent performance

Ken Moffat zarniwhoop at ntlworld.com
Wed Jan 20 13:35:03 PST 2016

On Wed, Jan 20, 2016 at 01:03:35PM -0700, Lloyd Brown wrote:
> Something else very odd, as well:
> I was just running glxgears (good performance) on one display, and then
> when I ran glxinfo on a second display, the glxgears performance dropped
> significantly, and glxgears disappeared from the output of nvidia-smi.
> Here's some example output from the glxgears; you can see about the time
> that I ran glxinfo in a separate shell, on a separate display:
> > [lbrown at m8g-1-8 ~]$ DISPLAY=:0.0 glxgears
> > Running synchronized to the vertical refresh.  The framerate should be
> > approximately the same as the monitor refresh rate.

O/T response (I think I understand what you are trying to do, but the
temptation to say this is just too great) -

LOL, for some of us, that last sentence you quoted is true (approx
60fps in my case on current/recent AMD and intel drivers)

> > 62559 frames in 5.0 seconds = 12511.681 FPS
> > 65114 frames in 5.0 seconds = 13022.790 FPS
> > 34837 frames in 5.0 seconds = 6966.968 FPS
> > 10710 frames in 5.0 seconds = 2141.983 FPS
> > 10645 frames in 5.0 seconds = 2128.814 FPS
> Now, the "slow-running" glxgears instance is closer to 350 or 375 FPS,
> so this is still better.  But it really appears that Xorg has some kind
> of resource shared between the instances.  I don't see how else one Xorg
> display could have this kind of effect on another.

You mentione 'nvidia-smi' so you appear to be using a binary driver.
If you don't get any useful ideas here, maybe ask on an nvidia list
or forum ?

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