The latency information has been obtained empirically from
measurements taken on Haswell and Ivy Bridge.
---
.../drivers/dri/i965/brw_schedule_instructions.cpp | 41 ++++++++++++++++++++++
1 file changed, 41 insertions(+)
diff --git a/src/mesa/drivers/dri/i965/brw_schedule_instructions.cpp
b/src/mesa/drivers/dri/i965/brw_schedule_instructions.cpp
index 944b5c8..cbfaabe 100644
--- a/src/mesa/drivers/dri/i965/brw_schedule_instructions.cpp
+++ b/src/mesa/drivers/dri/i965/brw_schedule_instructions.cpp
@@ -329,6 +329,47 @@ schedule_node::set_latency_gen7(bool is_haswell)
latency = 200;
break;
+ case SHADER_OPCODE_UNTYPED_ATOMIC:
+ /* Test code:
+ * mov(8) g112<1>ud 0x00000000ud { align1 WE_all 1Q };
+ * mov(1) g112.7<1>ud g1.7<0,1,0>ud { align1 WE_all };
+ * mov(8) g113<1>ud 0x00000000ud { align1 WE_normal 1Q
};
+ * send(8) g4<1>ud g112<8,8,1>ud
+ * data (38, 5, 6) mlen 2 rlen 1 { align1 WE_normal 1Q
};
+ *
+ * Running it 100 times as fragment shader on a 128x128 quad
+ * gives an average latency of 13867 cycles per atomic op,
+ * standard deviation 3%. Note that this is a rather
+ * pessimistic estimate, the actual latency in cases with few
+ * collisions between threads and favorable pipelining has been
+ * seen to be reduced by a factor of 100.
+ */
+ latency = 14000;
+ break;
+
+ case SHADER_OPCODE_UNTYPED_SURFACE_READ:
+ /* Test code:
+ * mov(8) g112<1>UD 0x00000000UD { align1 WE_all 1Q };
+ * mov(1) g112.7<1>UD g1.7<0,1,0>UD { align1 WE_all };
+ * mov(8) g113<1>UD 0x00000000UD { align1 WE_normal 1Q
};
+ * send(8) g4<1>UD g112<8,8,1>UD
+ * data (38, 6, 5) mlen 2 rlen 1 { align1 WE_normal 1Q
};
+ * .
+ * . [repeats 8 times]
+ * .
+ * mov(8) g112<1>UD 0x00000000UD { align1 WE_all 1Q };
+ * mov(1) g112.7<1>UD g1.7<0,1,0>UD { align1 WE_all };
+ * mov(8) g113<1>UD 0x00000000UD { align1 WE_normal 1Q
};
+ * send(8) g4<1>UD g112<8,8,1>UD
+ * data (38, 6, 5) mlen 2 rlen 1 { align1 WE_normal 1Q
};
+ *
+ * Running it 100 times as fragment shader on a 128x128 quad
+ * gives an average latency of 583 cycles per surface read,
+ * standard deviation 0.9%.
+ */
+ latency = is_haswell ? 300 : 600;
+ break;
+
default:
/* 2 cycles:
* mul(8) g4<1>F g2<0,1,0>F 0.5F { align1 WE_normal 1Q };
--
1.8.3.4
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