Buffer Damage

[Simon Ser]

On Monday, January 4th, 2021 at 1:36 PM, Vlad Zahorodnii <vlad.zahorodnii at kde.org> wrote:

> On 1/4/21 2:05 PM, Simon Ser wrote:
> > I don't think these would benefit from the optimization you're
> > suggesting. They don't cycle between pre-rendered buffers, for
> > instance.
>
> No, no, it was just an example when the surface damage and the buffer
> damage might be different, I don't necessarily want to optimize that
> extremely rare case. The issue is that the compositor has simply no idea
> how exactly the client utilizes the buffers. Keeping the last N surface
> damages and accumulating them is a good heuristic, but it may produce
> incorrect results in some cases + it is redundant if the app uses
> hardware acceleration.
>
> The bottom line is that shared memory client buffers tank performance
> and something should be probably done about it.

OK, this still doesn't explain which/how/why existing clients would
benefit from the optimization, and how much performance will really
improve in practice.