Re: [Mesa3d-dev] gallium cached bufmgr busy change

[Luca B. <luc...@gm...>]

> The fencing solution isn't near as efficent from what I can see, as it
> is designed around fences not buffer busy, I'll see if I can give it a try,
> but I suspect it look and smell like a hack.

The problem I see is that while fenced is guaranteed to make at most
one fence_signalled query for a busy buffer per allocation, cached
could potentially query the busy status of _all_ destroyed buffers for
every allocation.

The reason of this is that fenced orders the buffers in fence order
and stops at the first busy one, only handing them to the lower layer
(e.g. cached) once they are no longer busy.

If kernel calls are used instead of userspace fencing, the problem
probably gets worse.

So IMHO it should be much more efficient to use fenced over cached
(perhaps with slab between them too).