[Mesa-dev] [PATCH] r600g: remove one pointless flush

[Vadim Girlin]

On Fri, 2011-10-28 at 23:16 +0200, Marek Olšák wrote:
> On Fri, Oct 28, 2011 at 10:52 PM, Vadim Girlin <vadimgirlin at gmail.com> wrote:
> > On Fri, 2011-10-28 at 19:47 +0200, Marek Olšák wrote:
> >> I've got no idea what the flush was good for, but it's useless from
> >> the looks of it. The rest of the patch is just a cleanup resulting
> >> from some of the variables being no longer used for anything useful.
> >>
> >> There are no piglit regressions.
> >
> > It was intended to handle multiple interleaved query and conditional
> > render calls with single query object (in this case in theory we may
> > have multiple outstanding queries in current CS and separate data block
> > in the buffer for each query, with possible buffer overflow). I wasn't
> 
> Do you mean this?
> 
> while (1) {
>   begin_query(q);
>   draw();
>   end_query(q);
>   render_condition(q);
>   draw();
>   render_condition(NULL);
> }
> 
> begin_query always resets query results to 0 anyway, so in theory, we
> could re-use the same data block over and over again. 

I think it's possible to run this loop without flushes, so we'll have
multiple queries queued in current cs. From the driver point of view
these queries will be executed simultaneously after flush, that's why we
need to reserve and initialize separate data blocks for them.

Vadim

> I think the only
> case where buffer overflow may happen is:
> 
> begin_query(q);
> while (1) {
>   draw();
>   suspend_queries(); // flush or u_blitter
>   resume_queries();
> }
> end_query(q);
> 
> Correct?
> 
> Marek