Code review comment for lp:~vanvugt/mir/double

> * A client that's keeping up will be in-phase with composition. That
> * means it will stay, or quickly equalize at a point where there are
> * no client buffers still held when composition finishes.

This criterion only works well when the client is actually trying to keep up with the compositor (i.e. 60Hz). Clients that refresh less often on purpose or only when reacting to user input will become triple-buffered if the compositor is triggered by another source and they are not updating fast enough.

This happens, for example, if we run both mir_demo_client_egltriangle and mir_demo_client_fingerpaint. The frames from egltriangle trigger the compositor and cause mir_demo_client_fingerpaint to become triple-buffered after a short while. The same happens if we just have mir_demo_client_fingerpaint and move its surface around in the demo shell.

We probably need additional logic/heurestics to make this work properly (haven't thought through what that logic might be, though).