(In reply to comment #0)
> For example, Unigine Tropics benchmark gives 20fps, but with vblank_mode=0
> it's 54fps.

I can only reproduce this with vblank_mode=2 or =3, though AFAICT the default
is 2.

> Games that don't turn off vsync by themselves suffer from this as well.

Actually, as long as the game can sustain at least 60 fps (or whatever the
display refresh rate is) with vblank_mode < 2, it should still get 60 fps with
vblank_mode >= 2, and IME that's indeed the case with a lot of games.

The issue with Tropics is that it can only sustain just below 60 fps, which
becomes 30 fps (half the refresh rate, since it misses every other vertical
blank period) with sync-to-vblank, and then there are some scenes where it
drops even lower.

We will hopefully be able to handle this better with DRI3/Present.