[regression] GL(X) apps don't have vsync when running under XMir

[Daniel van Vugt]

When using XMir, GL apps are not synchronized to vblank correctly. For example using glxgears...

XMir:
Running synchronized to the vertical refresh. The framerate should be
approximately the same as the monitor refresh rate.
5632 frames in 5.0 seconds = 1126.334 FPS
5136 frames in 5.0 seconds = 1027.137 FPS
4686 frames in 5.0 seconds = 937.086 FPS
4519 frames in 5.0 seconds = 903.775 FPS
4469 frames in 5.0 seconds = 893.723 FPS
10179 frames in 5.0 seconds = 2035.627 FPS

Regular X:
Running synchronized to the vertical refresh. The framerate should be
approximately the same as the monitor refresh rate.
306 frames in 5.0 seconds = 61.115 FPS
301 frames in 5.0 seconds = 60.080 FPS
302 frames in 5.0 seconds = 60.275 FPS
301 frames in 5.0 seconds = 60.081 FPS
301 frames in 5.0 seconds = 60.078 FPS
301 frames in 5.0 seconds = 60.081 FPS

[Daniel van Vugt (vanvugt)]

This causes unwanted overheating and fan noise in the least.

[Daniel van Vugt (vanvugt)]

I'm trying to attach system information but apport-collect and ubuntu-bug don't seem to be working for the new Mir-related packages.

[kevin gunn (kgunn72)]

after some discussion to be clear - this does not lead to tearing.
the lack of throttling is at the glx level not the mir level

however, lacking a correction for this is still sub optimal for power.

[Daniel van Vugt (vanvugt)]

I suspect this bug also exists in the new Xmir. Need to confirm.

[Daniel van Vugt (vanvugt)]

Verified this bug appears fixed with the latest trunk Xmir code. However the fix is an illusion. It's actually bug 1502738. And if you enable the fix that's ready for that bug then this bug reoccurs.

[Daniel van Vugt (vanvugt)]

Invalid. The bug does not exist at all right now. And hopefully won't exist again.