[Mesa-dev] [PATCH 07/15] i965/blorp: Use 16 pixel dispatch on Gen7 when there is a WM program.

[Kenneth Graunke]

On 05/23/2012 07:45 AM, Paul Berry wrote:
> On 22 May 2012 13:02, Eric Anholt <eric at anholt.net
> <mailto:eric at anholt.net>> wrote:
>
>     On Fri, 11 May 2012 11:03:50 -0700, Paul Berry
>     <stereotype441 at gmail.com <mailto:stereotype441 at gmail.com>> wrote:
>      > When executing a blorp operation on Gen7 that does not need a WM
>      > program (i.e. a HiZ operation), we use 32-pixel dispatch mode because
>      > it's faster.  However, when executing a blorp operation that does
>     need
>      > a WM program, we need to use 16-pixel dispatch, because blorp WM
>      > programs are compiled assuming 16-pixel dispatch.
>
>     I didn't think dispatch mode means anything unless you're actually
>     dispatching a thread (though I could see how having no dispatch mode set
>     might anger things).  Basically, I'm thinking just always set 16, unless
>     there is some efficiency reason I don't know of.
>
>
> I don't honestly know.  Chad, I inherited the 32-pixel dispatch from
> your HiZ code, and assumed you did it on purpose because it was faster.
> But I didn't actually do any tests.  Do you have any thoughts about this?

I recall Chad saying that not setting thread dispatch broke horribly, so 
since he had enable thread dispatch, he picked the widest mode.