From: Francisco Jerez Date: Fri, 9 Dec 2016 03:18:00 +0000 (-0800) Subject: i965/fs: Fetch one cacheline of pull constants at a time. X-Git-Url: https://git.libre-soc.org/?a=commitdiff_plain;h=b56fa830c6095;p=mesa.git i965/fs: Fetch one cacheline of pull constants at a time. Asking the DC for less than one cacheline (4 owords) of data for uniform pull constants is suboptimal because the DC cannot request less than that from L3, resulting in wasted bandwidth and unnecessary message dispatch overhead, and exacerbating the IVB L3 serialization bug. The following table summarizes the overall framerate improvement (with statistical significance of 5% and sample size ~10) from the whole series up to this patch for several benchmarks and hardware generations: | SKL | BDW | HSW SynMark2 OglShMapPcf | 24.63% ±0.45% | 4.01% ±0.70% | 10.31% ±0.38% GfxBench4 gl_manhattan31 | 5.93% ±0.35% | 3.92% ±0.31% | 6.62% ±0.22% GfxBench4 gl_4 | 2.52% ±0.44% | 1.23% ±0.10% | N/A Unigine Valley | 0.83% ±0.17% | 0.23% ±0.05% | 0.74% ±0.45% Note that there are two versions of the Manhattan demo shipped with GfxBench4, one of them is the original gl_manhattan demo which doesn't use UBOs, so this patch will have no effect on it, and another one is the gl_manhattan31 demo based on GL 4.3/GLES 3.1, which this patch benefits as shown above. I haven't observed any statistically significant regressions in the benchmarks I have at hand. Note that the comparatively huge improvement on SKL in the OglShMapPcf test case is due to the combined effect of this patch and the register pressure benefit on SKL+ of "i965/fs: Switch to the constant cache for uniform pull constants.", part of the same series. Going up to 8 oword blocks would improve performance of pull constants even more, but at the cost of some additional bandwidth and register pressure, so it would have to be done on-demand based on the number of constants actually used by the shader. v2: Fix for Gen4 and 5. v3: Non-trivial rebase. Rework to allow the visitor specifiy arbitrary pull constant block sizes. Reviewed-by: Kenneth Graunke --- diff --git a/src/mesa/drivers/dri/i965/brw_fs.cpp b/src/mesa/drivers/dri/i965/brw_fs.cpp index 977fd8c35f5..671b44bd50d 100644 --- a/src/mesa/drivers/dri/i965/brw_fs.cpp +++ b/src/mesa/drivers/dri/i965/brw_fs.cpp @@ -2111,25 +2111,22 @@ fs_visitor::lower_constant_loads() if (pull_index == -1) continue; - const unsigned index = stage_prog_data->binding_table.pull_constants_start; - fs_reg dst; - - if (type_sz(inst->src[i].type) <= 4) - dst = vgrf(glsl_type::float_type); - else - dst = vgrf(glsl_type::double_type); - assert(inst->src[i].stride == 0); - const fs_builder ubld = ibld.exec_all().group(4, 0); - struct brw_reg offset = brw_imm_ud((unsigned)(pull_index * 4) & ~15); + const unsigned index = stage_prog_data->binding_table.pull_constants_start; + const unsigned block_sz = 64; /* Fetch one cacheline at a time. */ + const fs_builder ubld = ibld.exec_all().group(block_sz / 4, 0); + const fs_reg dst = ubld.vgrf(BRW_REGISTER_TYPE_UD); + const unsigned base = pull_index * 4; + ubld.emit(FS_OPCODE_UNIFORM_PULL_CONSTANT_LOAD, - dst, brw_imm_ud(index), offset); + dst, brw_imm_ud(index), brw_imm_ud(base & ~(block_sz - 1))); /* Rewrite the instruction to use the temporary VGRF. */ inst->src[i].file = VGRF; inst->src[i].nr = dst.nr; - inst->src[i].offset = (pull_index & 3) * 4 + inst->src[i].offset % 4; + inst->src[i].offset = (base & (block_sz - 1)) + + inst->src[i].offset % 4; brw_mark_surface_used(prog_data, index); } diff --git a/src/mesa/drivers/dri/i965/brw_fs_nir.cpp b/src/mesa/drivers/dri/i965/brw_fs_nir.cpp index 7df74232457..9f2729a9b6e 100644 --- a/src/mesa/drivers/dri/i965/brw_fs_nir.cpp +++ b/src/mesa/drivers/dri/i965/brw_fs_nir.cpp @@ -4059,21 +4059,23 @@ fs_visitor::nir_emit_intrinsic(const fs_builder &bld, nir_intrinsic_instr *instr * and we have to split it if necessary. */ const unsigned type_size = type_sz(dest.type); - const fs_builder ubld = bld.exec_all().group(4, 0); - const fs_reg packed_consts = ubld.vgrf(BRW_REGISTER_TYPE_F); + const unsigned block_sz = 64; /* Fetch one cacheline at a time. */ + const fs_builder ubld = bld.exec_all().group(block_sz / 4, 0); + const fs_reg packed_consts = ubld.vgrf(BRW_REGISTER_TYPE_UD); for (unsigned c = 0; c < instr->num_components;) { const unsigned base = const_offset->u32[0] + c * type_size; - - /* Number of usable components in the next 16B-aligned load */ + /* Number of usable components in the next block-aligned load. */ const unsigned count = MIN2(instr->num_components - c, - (16 - base % 16) / type_size); + (block_sz - base % block_sz) / type_size); ubld.emit(FS_OPCODE_UNIFORM_PULL_CONSTANT_LOAD, - packed_consts, surf_index, brw_imm_ud(base & ~15)); + packed_consts, surf_index, + brw_imm_ud(base & ~(block_sz - 1))); const fs_reg consts = - retype(byte_offset(packed_consts, base & 15), dest.type); + retype(byte_offset(packed_consts, base & (block_sz - 1)), + dest.type); for (unsigned d = 0; d < count; d++) bld.MOV(offset(dest, bld, c + d), component(consts, d));