On Fri, Jan 9, 2015 at 10:33 PM, Kenneth Graunke <kenn...@whitecape.org> wrote: > On Friday, January 09, 2015 09:31:35 PM Matt Turner wrote: >> On Fri, Jan 9, 2015 at 8:46 PM, Kenneth Graunke <kenn...@whitecape.org> >> wrote: >> > When doing repclears, we only want to use the SIMD16 program, not the >> > SIMD8 one. Kristian added this to the Gen7+ code, but apparently we >> > missed it in the Gen6 code. This patch copies that code over. >> > >> > Approximately doubles the performance in a clear microbenchmark from >> > mesa-demos (clearspd -width 500 -height 500 +color) on Sandybridge. >> >> What was actually happening? We were attempting to use a nonexistent >> SIMD8 program as well? Or the SIMD16 repclear program just wasn't >> getting used at all? > > When compiling, we only compile a SIMD16 program - no SIMD8 at all. > > Since there's no SIMD8 program, prog_data->prog_offset_16 == 0 (the SIMD16 > program is at the beginning). > > So then...in gen6_wm_state.c:145, we set GEN6_WM_8_DISPATCH_ENABLE...with > the right dispatch_grf_start_reg...but with the SIMD16 repdata shader. > > So...we ran the SIMD16 repclear shader...with a send(16)...in SIMD8 dispatch > mode. I thought that was totally invalid, but it seems to be kind of working. > Probably just taking twice as many pixel shader dispatches to do the job... > which would correspond to the half speed problem.
Heh, awesome. That seems plausible. Reviewed-by: Matt Turner <matts...@gmail.com> _______________________________________________ mesa-dev mailing list mesa-dev@lists.freedesktop.org http://lists.freedesktop.org/mailman/listinfo/mesa-dev
