[Mesa-dev] [PATCH 02/14] st/mesa: add a simple path to BufferData if it only discards buffer contents

[Eric Anholt]

Marek Olšák <maraeo at gmail.com> writes:

> The next patch makes sure _NEW_BUFFER_OBJECT is not needlessly set
> for this code.

This seems like a pretty dubious optimization -- on UMA systems you're
increasing the memory bandwidth usage in the "&& data" case, and only
trying to eliminate update_array_object_max_element, which also happens
with _NEW_PROGRAM (I bet it's true every time that a _NEW_BUFFER_OBJECT
was flagged, anyway).

In short, for the Mesa core change, I'd like to see some actual
performance justification on this one.
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