You didn't help about my question, and did not answer where the fbCopyNtoN and
fbCopyArea hide. I shall repeat my simple and humble question again : are the
fbCopyNtoN() and fbCopyarea() in UXA implemented in Xorg fb/fbcopy?
------------------ ???????? ------------------
??????: "Chris Wilson";<[email protected]>;
????????: 2013??9??23??(??????) ????5:40
??????: "??????"<[email protected]>;
????: "xorg-devel"<[email protected]>;
????: Re: ?????? Where does Xorg fallbackto ?
On Mon, Sep 23, 2013 at 05:13:19PM +0800, ?????? wrote:
> The right answer is don't start from there. For fallbacks, UXA uses a
> GTT mapping so every surface is actually in WC memory - every read is
> treated as uncached, and fallbacks do a lot of reads. Effort spent
> optimising the fb layer in this case is completely wasted.
> -Chris
>
> I don't quite understand that. Or you mean that fbCopyArea() is
> wrapped?
The fb* functions are provided by the xserver. What I am trying to point
out is that UXA fundamentally uses hw in such a way that prevents
optimisation. Every pointer read in fb* is uncached. Optimising an
already fairly well optimised implementation will at most gain less than
a percent overall. Switching to a different mapping and implementating
migration will gain an order of magnitude performance improvement.
Implementing 2D acceleration will gain between 5x-10x over and above the
optimal fb implementation.
If you read the driver more carefully you will find these answers
already there.
-Chris
--
Chris Wilson, Intel Open Source Technology Centre
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