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Old 06-06-10, 01:59 PM   #4
Linux kernel hacker
Join Date: Feb 2009
Location: Ottawa, Canada
Posts: 173
Default Re: 256.29: Jerky VDPAU HD playback in MythTV

Originally Posted by Stephen Warren View Post
mlord, can you .. see if there's a difference in which PowerMizer level is selected
Both versions use "adaptive control", and both switch into high-gear for playback, and stay there. So that part is working well, thanks.

But I have another idea: There's an app (which I wrote) managing the VFD display in my Antec case, and it normally queries/displays the GPU temperature every 5-10 seconds and displays it. Here's the query command it uses:

nvidia-settings -q :0.0/GPUCoreTemp

That command seems to take between 130 and 180 milliseconds to invoke/complete each time, and once in a while (every minute or so) this appears to cause a jerkiness in playback with the 256.2x beta drivers, but not with the earlier 195.xx drivers.

Removing the temperature polling seems to smooth things out here with 256.2x, so that's what I've now done.

I wonder if temperature query from commandline (as per above) grabs a mutex or something inside the driver, and holds it a tad long? Or perhaps creates a priority-inversion situation when pre-empted by the mythtv vdpau playback code?

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