[Mesa-dev] r300 poke magical go faster register

[Tom Morton]

Hi people,

On the perf/vertexrate test, and on my terrain engine I see big big
performance boosts from this patch (I have no idea what I'm doing but on
my RV515 i see tris/sec go from 8 million to 15 million - kms only):

diff --git a/src/mesa/drivers/dri/r300/r300_reg.h
b/src/mesa/drivers/dri/r300/r300_reg.h
index ac93563..0093eb5 100644
--- a/src/mesa/drivers/dri/r300/r300_reg.h
+++ b/src/mesa/drivers/dri/r300/r300_reg.h
@@ -170,6 +170,7 @@ USE OR OTHER DEALINGS IN THE SOFTWARE.
 #      define R300_VC_32BIT_SWAP               (2 << 0)
 /* Half-dword swap: 0xAABBCCDD becomes 0xCCDDAABB */
 #      define R300_VC_HALF_DWORD_SWAP          (3 << 0)
+#      define R300_VC_FORCE_PREFETCH           (1 << 5)
 /* The TCL engine will not be used (as it is logically or even
physically removed) */
 #      define R300_VAP_TCL_BYPASS              (1 << 8)
 /* Read only flag if TCL engine is busy. */
diff --git a/src/mesa/drivers/dri/r300/r300_render.c
b/src/mesa/drivers/dri/r300/r300_render.c
index bb8f914..5b9983f 100644
--- a/src/mesa/drivers/dri/r300/r300_render.c
+++ b/src/mesa/drivers/dri/r300/r300_render.c
@@ -260,7 +260,7 @@ static void r300EmitAOS(r300ContextPtr rmesa, GLuint
nr, GLuint offset)

                BEGIN_BATCH(sz+2+(nr * 2));
                OUT_BATCH_PACKET3(R300_PACKET3_3D_LOAD_VBPNTR, sz - 1);
-               OUT_BATCH(nr);
+               OUT_BATCH(nr | R300_VC_FORCE_PREFETCH);

                for (i = 0; i + 1 < nr; i += 2) {
                        OUT_BATCH((rmesa->radeon.tcl.aos[i].components
<< 0) |



is this a good idea?

-- 
Tom