[Mesa-dev] [PATCH] r600g: order atom emission v2

[Jerome Glisse]

On Thu, Sep 6, 2012 at 4:10 PM, Marek Olšák <maraeo at gmail.com> wrote:
> On Thu, Sep 6, 2012 at 8:34 PM, Jerome Glisse <j.glisse at gmail.com> wrote:
>> On Thu, Sep 6, 2012 at 2:29 PM, Marek Olšák <maraeo at gmail.com> wrote:
>>> This looks good to me. It's funny to see the r300g architecture being
>>> re-implemented in r600g. :)
>>>
>>> There's one optimization that r300g has that this patch doesn't. r300g
>>> keeps the index of the first and the last dirty atom and the loops
>>> over the list of atoms look like this:
>>> for (i = first_dirty; i <= last_dirty; i++)
>>>
>>> And after emission:
>>> first_dirty = some large number;
>>> last_dirty= 0;
>>>
>>> The atoms should be ordered according to how frequently they are
>>> updated (except when the ordering is required by the hw). But most
>>> importantly, if there are no state changes, the loops are trivially
>>> skipped.
>>>
>>> Marek
>>
>> Don't think this optimization is worth it, there won't be much more
>> than 32 atom in the end and it definitely can't be ordered from most
>> frequent to less frequent as some of the stuff need to be at the last
>> being emitted and they are frequent one (primitive type for instance).
>
> I didn't say all atoms *must* be sorted. I meant that some (most?)
> atoms can be sorted, i.e. you can have some atoms at fixed positions
> (like the primitype type or the seamless cubemap state), but you have
> always at least *some* freedom where you put the rest. The ordering I
> had in mind was actually from the least frequent to the most frequent,
> in other words, from the framebuffer (least frequent) to shaders to
> textures to constant buffers to vertex buffers (most frequent).
>
> Of course, the code should document which atoms must have fixed
> positions along with an explanation. The comment that all atom
> positions must not be changed isn't enough, because it's not true.
>
> Marek

I won't try to find which atom can have complete floating position, i
am just grouping together register that are always emitted together in
fglrx and then i position this group relative to each other according
to fglrx position. That means all atom are always emitted in a
specific order. So there won't be any freedom. The only freedom i can
think of is btw 2 position forced atom and that make the sorting
completely useless and complicated.

Cheers,
Jerome