[Mesa-dev] [PATCH v2 5/9] mesa: Handle QUERY_RESULT_NO_WAIT in GetQueryObject{ui64}v

[Kenneth Graunke]

On 03/27/2014 11:34 PM, Kenneth Graunke wrote:
> On 03/27/2014 01:59 PM, Rafal Mielniczuk wrote:
>> Just return and do nothing if query result is not yet available
>>
>> Signed-off-by: Rafal Mielniczuk <rafal.mielniczuk2 at gmail.com>
>> ---
>>  src/mesa/main/queryobj.c | 16 ++++++++++++++++
>>  1 file changed, 16 insertions(+)
>>
>> diff --git a/src/mesa/main/queryobj.c b/src/mesa/main/queryobj.c
>> index 86e7c3a..d2d9fa7 100644
>> --- a/src/mesa/main/queryobj.c
>> +++ b/src/mesa/main/queryobj.c
>> @@ -594,6 +594,10 @@ _mesa_GetQueryObjectiv(GLuint id, GLenum pname, GLint *params)
>>     }
>>  
>>     switch (pname) {
>> +      case GL_QUERY_RESULT_NO_WAIT:
>> +         if (!q->Ready)
>> +            return;
>> +         //else fall through
> 
> We don't usually use C++ style comments in Mesa.  I would do:
> 
> case GL_QUERY_NO_WAIT:
>    if (!q->Ready)
>        return;
>    /* fallthrough */
> case GL_QUERY_RESULT_ARB:
> 
> Other than that, patches 1-6 are:
> Reviewed-by: Kenneth Graunke <kenneth at whitecape.org>

Actually, I take that back...I don't think this is what we want for GPU
drivers.  (It's probably reasonable for software drivers though.)

When a buffer object is bound to GL_QUERY_BUFFER, the idea is that the
GL_QUERY_RESULT/GL_QUERY_RESULT_NO_WAIT queries should emit GPU commands
to deliver the query result into the buffer object.

The query result may not actually be available yet (so, q->Ready ==
false), but the GPU commands to obtain the result have already been
submitted.  Since any GPU commands we submit will happen after those,
they can work with the result as if it's available...because it will be
by the time they run.

At least, that's my understanding right now.  So, we need a way to know
if a query result is "in flight, but done" (i.e. all commands to compute
it have been submitted, but may not have run yet), and a way to ask the
driver to deliver it to a particular buffer object/offset.  That
probably means two new driver hooks, but I'm not quite sure what they
should look like just yet.

So, patches 1-4 and 6 are:
Reviewed-by: Kenneth Graunke <kenneth at whitecape.org>

I won't be around next week, but I'd be happy to help look into this
when I'm back.  (Unless, of course, others beat me to it...) :)

Thanks again for your work on this!

--Ken

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