[Mesa-dev] [PATCH 2/2] i965/bufmgr: s/BO_ALLOC_FOR_RENDER/BO_ALLOC_BUSY/

[Chris Wilson]

Quoting Jason Ekstrand (2017-08-19 23:07:48)
> "Alloc for render" is a terrible name for a flag because it means
> basically nothing.  What the flag really does is allocate a busy BO
> which someone theorized at one point in time would be more efficient if
> you're planning to immediately render to it.  If the flag really means
> "alloc a busy BO" we should just call it that.

The active part of it has always been "alloc idle". There are two
observable effects, for frequent reallocations reusing bo within the
active batch is very effective, with a secondary effect from mru to trim
rss; and for buffers being written immediately written to by the cpu
after allocation. It's not just theorized, it has a measurable impact.

But my 2c would be that BO_ALLOC_IDLE is the imperative. However, that
requires flipping all the callers.
-Chris