与基于模板的AutoTVM不同(会依赖手动模板定义搜索空间)，自动调度器不需要任何模板。用户只需要编写计算声明，而不需要任何调度命令或模板。自动调度器可以自动生产一个大的搜索空间，并在空间中找到一个好的调度。
本节以矩阵乘法为例
导入依赖包
import os
import numpy as np
import tvm
from tvm import te, auto_scheduler
Defining the Matrix Multiplication
首先，定义一个带有偏置的矩阵乘法。(注意：这儿使用的是TVM张量表达式中的标准操作)。主要区别在于函数定义的开头使用了register_workload装饰器。该函数应该返回一个输入/输出张量的列表。从这些张量中，自动调度器可以得到整个计算图。
@auto_scheduler.register_workload # Note the auto_scheduler decorator
def matmul_add(N, L, M, dtype):
A = te.placeholder((N, L), name="A", dtype=dtype)
B = te.placeholder((L, M), name="B", dtype=dtype)
C = te.placeholder((N, M), name="C", dtype=dtype)
k = te.reduce_axis((0, L), name="k")
matmul = te.compute(
(N, M),
lambda i, j: te.sum(A[i, k] * B[k, j], axis=k),
name="matmul",
attrs={"layout_free_placeholders": [B]}, # enable automatic layout transform for tensor B
)
out = te.compute((N, M), lambda i, j: matmul[i, j] + C[i, j], name="out")
return [A, B, C, out]
Create the search task
函数定义过后，现在可以为auto_scheduler创建一个搜索任务来进行搜索。我们指定这个矩阵乘法的特殊参数，在这个例子中，是对 大小的正方形矩阵的乘法。然后我们使用 N=L=M=1024 and dtype="float32" 创建一个搜索任务
用自定义目标提高性能
为了使 TVM 能够充分利用特定的硬件平台，你需要手动指定你的 CPU 能力。例如：
- 用
llvm -mcpu=core-avx2替换下面的llvm，以启用 AVX2 - 用
llvm -mcpu=skylake-avx512替换下面的llvm，以启用 AVX-512
target = tvm.target.Target("llvm")
N = L = M = 1024
task = tvm.auto_scheduler.SearchTask(func=matmul_add, args=(N, L, M, "float32"), target=target)
# Inspect the computational graph
print("Computational DAG:")过一些测量试验后，我们可以从日志文件中加载最佳调度并加以应用。
print(task.compute_dag)
运行结果：
Set Parameters for Auto-Scheduler
下一步，为自动调度设置参数。
num_measure_trials是我们在搜索过程中可以使用的测量试验的数量。为了快速演示，我们在本教程中只做了 10 次试验。在实践中，1000 是一个很好的搜索收敛值。你可以根据你的时间预算做更多的试验。- 此外，我们使用
RecordToFile来 log 测量记录到matmul.json文件中。这些测量记录可以用来查询历史最好的，恢复搜索，并在以后做更多的分析。 - 查阅 TuningOptions 了解参数的更多信息。
log_file = "matmul.json"
tune_option = auto_scheduler.TuningOptions(
num_measure_trials=10,
measure_callbacks=[auto_scheduler.RecordToFile(log_file)],
verbose=2,
)
Run the search
现在所有的输入都已经准备好了，可以启动搜索，让自动调度发挥下的它的魔力。经过一些测量试验后，我们可以从日志文件中加载最佳调度并加以应用。
# Run auto-tuning (search)
task.tune(tune_option)
# Apply the best schedule
sch, args = task.apply_best(log_file)
运行结果：
----------------------------------------------------------------------
------------------------------ [ Search ]
----------------------------------------------------------------------
Generate Sketches #s: 3
Sample Initial Population #s: 2015 fail_ct: 3 Time elapsed: 0.44
GA Iter: 0 Max score: 0.9999 Min score: 0.9216 #Pop: 128 #M+: 0 #M-: 0
GA Iter: 4 Max score: 0.9999 Min score: 0.9879 #Pop: 128 #M+: 1379 #M-: 67
EvolutionarySearch #s: 128 Time elapsed: 1.67
----------------------------------------------------------------------
------------------------------ [ Measure ]
----------------------------------------------------------------------
Get 10 programs to measure:
..........**********
==================================================
No: 1 GFLOPS: 216.46 / 216.46 results: MeasureResult(cost:[0.0099], error_no:0, all_cost:0.70, Tstamp:1658493558.70)
==================================================
Placeholder: A, B, C
parallel i.0@j.0@ (0,8)
matmul auto_unroll: 64
for i.1 (0,4)
for j.1 (0,32)
for k.0 (0,32)
for i.2 (0,8)
for j.2 (0,2)
for k.1 (0,32)
for i.3 (0,8)
vectorize j.3 (0,8)
matmul = ...
for i.1 (0,256)
for j.1 (0,512)
out = ...
==================================================
No: 2 GFLOPS: 122.79 / 216.46 results: MeasureResult(cost:[0.0175], error_no:0, all_cost:0.73, Tstamp:1658493559.09)
==================================================
Placeholder: A, B, C
matmul auto_unroll: 512
parallel i.0@j.0@i.1@j.1@ (0,1024)
for k.0 (0,256)
for j.2 (0,256)
for k.1 (0,4)
for i.3 (0,2)
vectorize j.3 (0,2)
matmul = ...
parallel i (0,1024)
for j (0,1024)
out = ...
==================================================
No: 3 GFLOPS: 111.42 / 216.46 results: MeasureResult(cost:[0.0193], error_no:0, all_cost:0.51, Tstamp:1658493559.38)
==================================================
Placeholder: A, B, C
parallel i.0@j.0@ (0,128)
matmul auto_unroll: 64
for j.1 (0,2)
for k.0 (0,16)
for i.2 (0,512)
for k.1 (0,64)
for i.3 (0,2)
vectorize j.3 (0,4)
matmul = ...
for i.1 (0,1024)
vectorize j.1 (0,8)
out = ...
==================================================
No: 4 GFLOPS: 34.44 / 216.46 results: MeasureResult(cost:[0.0624], error_no:0, all_cost:0.72, Tstamp:1658493559.74)
==================================================
Placeholder: A, B, C
parallel i.0@j.0@ (0,1024)
matmul auto_unroll: 64
for k.0 (0,32)
for i.2 (0,32)
for j.2 (0,2)
for k.1 (0,32)
for i.3 (0,16)
matmul = ...
for i.1 (0,512)
vectorize j.1 (0,2)
out = ...
==================================================
No: 5 GFLOPS: 22.98 / 216.46 results: MeasureResult(cost:[0.0935], error_no:0, all_cost:0.56, Tstamp:1658493560.21)
==================================================
Placeholder: A, B, C
parallel i.0@j.0@ (0,2048)
for i.1 (0,8)
for k.0 (0,1024)
for i.3 (0,64)
matmul = ...
for i.1 (0,512)
out = ...
==================================================
No: 6 GFLOPS: 11.09 / 216.46 results: MeasureResult(cost:[0.1938], error_no:0, all_cost:1.16, Tstamp:1658493561.09)
==================================================
Placeholder: A, B, C
parallel i.0@j.0@ (0,2)
matmul auto_unroll: 16
for i.1 (0,8)
for j.1 (0,256)
for k.0 (0,512)
for i.2 (0,8)
for j.2 (0,4)
for k.1 (0,2)
for i.3 (0,8)
matmul = ...
for i.1 (0,512)
for j.1 (0,1024)
out = ...
==================================================
No: 7 GFLOPS: 1.52 / 216.46 results: MeasureResult(cost:[1.4124], error_no:0, all_cost:5.96, Tstamp:1658493566.86)
==================================================
Placeholder: A, B, C
parallel i.0@j.0@ (0,2)
for i.1 (0,8)
for j.1 (0,32)
for k.0 (0,256)
for j.2 (0,32)
for k.1 (0,4)
for i.3 (0,64)
matmul = ...
for i.1 (0,512)
for j.1 (0,1024)
out = ...
==================================================
No: 8 GFLOPS: 64.39 / 216.46 results: MeasureResult(cost:[0.0334], error_no:0, all_cost:1.44, Tstamp:1658493567.09)
==================================================
Placeholder: A, B, C
parallel i.0@j.0@ (0,512)
matmul auto_unroll: 512
for i.1 (0,8)
for j.1 (0,8)
for k.0 (0,32)
for k.1 (0,32)
for i.3 (0,16)
vectorize j.3 (0,2)
matmul = ...
for i.1 (0,128)
vectorize j.1 (0,16)
out = ...
==================================================
No: 9 GFLOPS: 36.16 / 216.46 results: MeasureResult(cost:[0.0594], error_no:0, all_cost:1.23, Tstamp:1658493567.43)
==================================================
Placeholder: A, B, C
matmul auto_unroll: 64
parallel i.0@j.0@ (0,8)
for i.1 (0,4)
for j.1 (0,2)
for k.0 (0,16)
for i.2 (0,4)
for k.1 (0,64)
for i.3 (0,64)
for j.3 (0,64)
matmul = ...
parallel i (0,1024)
for j (0,1024)
out = ...
==================================================
No: 10 GFLOPS: 23.41 / 216.46 results: MeasureResult(cost:[0.0918], error_no:0, all_cost:1.98, Tstamp:1658493567.90)
==================================================
Placeholder: A, B, C
matmul auto_unroll: 512
parallel i.0@j.0@ (0,8192)
for i.1 (0,32)
for k.0 (0,16)
for i.2 (0,2)
for j.2 (0,2)
for k.1 (0,64)
matmul = ...
parallel i (0,1024)
for j (0,1024)
out = ...
Time elapsed for measurement: 12.25 s
----------------------------------------------------------------------
------------------------------ [ Done ]
----------------------------------------------------------------------
Inspecting the Optimized Schedule
我们可以 lower 调度，看看自动调度后的 IR。自动调度器正确地进行了优化，包括多级平铺（tiling）、布局转换（layout transformation）、并行化（parallelization）、矢量化（vectorization）、解卷（unrolling）和运算符融合（operator fusion）。
print("Lowered TIR:")
print(tvm.lower(sch, args, simple_mode=True))
输出结果：
Lowered TIR:
@main = primfn(A_1: handle, B_1: handle, C_1: handle, out_1: handle) -> ()
attr = {"from_legacy_te_schedule": True, "global_symbol": "main", "tir.noalias": True}
buffers = {A: Buffer(A_2: Pointer(float32), float32, [1048576], []),
B: Buffer(B_2: Pointer(float32), float32, [1048576], []),
C: Buffer(C_2: Pointer(float32), float32, [1048576], []),
out: Buffer(out_2: Pointer(float32), float32, [1048576], [])}
buffer_map = {A_1: A, B_1: B, C_1: C, out_1: out}
preflattened_buffer_map = {A_1: A_3: Buffer(A_2, float32, [1024, 1024], []), B_1: B_3: Buffer(B_2, float32, [1024, 1024], []), C_1: C_3: Buffer(C_2, float32, [1024, 1024], []), out_1: out_3: Buffer(out_2, float32, [1024, 1024], [])} {
allocate(auto_scheduler_layout_transform: Pointer(global float32), float32, [1048576]), storage_scope = global {
for (ax0.ax1.fused.ax2.fused: int32, 0, 64) "parallel" {
for (ax3: int32, 0, 32) {
for (ax4: int32, 0, 2) {
for (ax5: int32, 0, 32) {
for (ax6: int32, 0, 8) {
auto_scheduler_layout_transform_1: Buffer(auto_scheduler_layout_transform, float32, [1048576], [])[(((((ax0.ax1.fused.ax2.fused*16384) + (ax3*512)) + (ax4*256)) + (ax5*8)) + ax6)] = B[(((((ax3*32768) + (ax5*1024)) + (ax0.ax1.fused.ax2.fused*16)) + (ax4*8)) + ax6)]
}
}
}
}
}
for (i.outer.j.outer.fused: int32, 0, 8) "parallel" {
allocate(matmul: Pointer(global float32), float32, [131072]), storage_scope = global {
for (i.outer.outer.inner: int32, 0, 4) {
for (j.outer.outer.inner: int32, 0, 32) {
for (i.outer.inner.init: int32, 0, 8) {
let cse_var_1: int32 = (((i.outer.outer.inner*32768) + (i.outer.inner.init*4096)) + (j.outer.outer.inner*16))
{
matmul_1: Buffer(matmul, float32, [131072], [])[ramp(cse_var_1, 1, 8)] = broadcast(0f32, 8)
matmul_1[ramp((cse_var_1 + 512), 1, 8)] = broadcast(0f32, 8)
matmul_1[ramp((cse_var_1 + 1024), 1, 8)] = broadcast(0f32, 8)
matmul_1[ramp((cse_var_1 + 1536), 1, 8)] = broadcast(0f32, 8)
matmul_1[ramp((cse_var_1 + 2048), 1, 8)] = broadcast(0f32, 8)
matmul_1[ramp((cse_var_1 + 2560), 1, 8)] = broadcast(0f32, 8)
matmul_1[ramp((cse_var_1 + 3072), 1, 8)] = broadcast(0f32, 8)
matmul_1[ramp((cse_var_1 + 3584), 1, 8)] = broadcast(0f32, 8)
matmul_1[ramp((cse_var_1 + 8), 1, 8)] = broadcast(0f32, 8)
matmul_1[ramp((cse_var_1 + 520), 1, 8)] = broadcast(0f32, 8)
matmul_1[ramp((cse_var_1 + 1032), 1, 8)] = broadcast(0f32, 8)
matmul_1[ramp((cse_var_1 + 1544), 1, 8)] = broadcast(0f32, 8)
matmul_1[ramp((cse_var_1 + 2056), 1, 8)] = broadcast(0f32, 8)
matmul_1[ramp((cse_var_1 + 2568), 1, 8)] = broadcast(0f32, 8)
matmul_1[ramp((cse_var_1 + 3080), 1, 8)] = broadcast(0f32, 8)
matmul_1[ramp((cse_var_1 + 3592), 1, 8)] = broadcast(0f32, 8)
}
}
for (k.outer: int32, 0, 32) {
for (i.outer.inner: int32, 0, 8) {
for (j.outer.inner: int32, 0, 2) {
for (k.inner: int32, 0, 32) {
let cse_var_11: int32 = ((((i.outer.outer.inner*32768) + (i.outer.inner*4096)) + (j.outer.outer.inner*16)) + (j.outer.inner*8))
let cse_var_10: int32 = (cse_var_11 + 512)
let cse_var_9: int32 = (cse_var_11 + 3584)
let cse_var_8: int32 = (cse_var_11 + 3072)
let cse_var_7: int32 = (cse_var_11 + 2560)
let cse_var_6: int32 = (cse_var_11 + 2048)
let cse_var_5: int32 = (cse_var_11 + 1536)
let cse_var_4: int32 = (cse_var_11 + 1024)
let cse_var_3: int32 = (((((floordiv(i.outer.j.outer.fused, 2)*262144) + (i.outer.outer.inner*65536)) + (i.outer.inner*8192)) + (k.outer*32)) + k.inner)
let cse_var_2: int32 = (((((floormod(i.outer.j.outer.fused, 2)*524288) + (j.outer.outer.inner*16384)) + (k.outer*512)) + (j.outer.inner*256)) + (k.inner*8))
{
matmul_1[ramp(cse_var_11, 1, 8)] = (matmul_1[ramp(cse_var_11, 1, 8)] + (broadcast(A[cse_var_3], 8)*auto_scheduler_layout_transform_1[ramp(cse_var_2, 1, 8)]))
matmul_1[ramp(cse_var_10, 1, 8)] = (matmul_1[ramp(cse_var_10, 1, 8)] + (broadcast(A[(cse_var_3 + 1024)], 8)*auto_scheduler_layout_transform_1[ramp(cse_var_2, 1, 8)]))
matmul_1[ramp(cse_var_4, 1, 8)] = (matmul_1[ramp(cse_var_4, 1, 8)] + (broadcast(A[(cse_var_3 + 2048)], 8)*auto_scheduler_layout_transform_1[ramp(cse_var_2, 1, 8)]))
matmul_1[ramp(cse_var_5, 1, 8)] = (matmul_1[ramp(cse_var_5, 1, 8)] + (broadcast(A[(cse_var_3 + 3072)], 8)*auto_scheduler_layout_transform_1[ramp(cse_var_2, 1, 8)]))
matmul_1[ramp(cse_var_6, 1, 8)] = (matmul_1[ramp(cse_var_6, 1, 8)] + (broadcast(A[(cse_var_3 + 4096)], 8)*auto_scheduler_layout_transform_1[ramp(cse_var_2, 1, 8)]))
matmul_1[ramp(cse_var_7, 1, 8)] = (matmul_1[ramp(cse_var_7, 1, 8)] + (broadcast(A[(cse_var_3 + 5120)], 8)*auto_scheduler_layout_transform_1[ramp(cse_var_2, 1, 8)]))
matmul_1[ramp(cse_var_8, 1, 8)] = (matmul_1[ramp(cse_var_8, 1, 8)] + (broadcast(A[(cse_var_3 + 6144)], 8)*auto_scheduler_layout_transform_1[ramp(cse_var_2, 1, 8)]))
matmul_1[ramp(cse_var_9, 1, 8)] = (matmul_1[ramp(cse_var_9, 1, 8)] + (broadcast(A[(cse_var_3 + 7168)], 8)*auto_scheduler_layout_transform_1[ramp(cse_var_2, 1, 8)]))
}
}
}
}
}
}
}
for (i.inner: int32, 0, 256) {
for (j.inner: int32, 0, 512) {
let cse_var_12: int32 = ((((floordiv(i.outer.j.outer.fused, 2)*262144) + (i.inner*1024)) + (floormod(i.outer.j.outer.fused, 2)*512)) + j.inner)
out[cse_var_12] = (matmul_1[((i.inner*512) + j.inner)] + C[cse_var_12])
}
}
}
}
}
}
Check correctness and evaluate performance
建立二进制文件，并检查其正确性（correctness）和性能（performance）
func = tvm.build(sch, args, target)
a_np = np.random.uniform(size=(N, L)).astype(np.float32)
b_np = np.random.uniform(size=(L, M)).astype(np.float32)
c_np = np.random.uniform(size=(N, M)).astype(np.float32)
out_np = a_np.dot(b_np) + c_np
dev = tvm.cpu()
a_tvm = tvm.nd.array(a_np, device=dev)
b_tvm = tvm.nd.array(b_np, device=dev)
c_tvm = tvm.nd.array(c_np, device=dev)
out_tvm = tvm.nd.empty(out_np.shape, device=dev)
func(a_tvm, b_tvm, c_tvm, out_tvm)
# Check results
np.testing.assert_allclose(out_np, out_tvm.numpy(), rtol=1e-3)
# Evaluate execution time.
evaluator = func.time_evaluator(func.entry_name, dev, min_repeat_ms=500)
print(
"Execution time of this operator: %.3f ms"
% (np.median(evaluator(a_tvm, b_tvm, c_tvm, out_tvm).results) * 1000)
)
运行结果：
Execution time of this operator: 10.171 ms
Using the record file
在搜索过程中，所有的测量记录都被 log 到记录文件 matmul.json。这些测量记录可以用来重新应用搜索结果，恢复搜索，并进行其他分析。
这里有一个例子，我们从一个文件中加载最佳调度，并打印出等效的 python 调度 API。这可以用于调试和学习自动调度的行为。
print("Equivalent python schedule:")
print(task.print_best(log_file))
输出结果：
Equivalent python schedule:
matmul_i, matmul_j, matmul_k = tuple(matmul.op.axis) + tuple(matmul.op.reduce_axis)
out_i, out_j = tuple(out.op.axis) + tuple(out.op.reduce_axis)
matmul_i_o_i, matmul_i_i = s[matmul].split(matmul_i, factor=8)
matmul_i_o_o_i, matmul_i_o_i = s[matmul].split(matmul_i_o_i, factor=8)
matmul_i_o_o_o, matmul_i_o_o_i = s[matmul].split(matmul_i_o_o_i, factor=4)
matmul_j_o_i, matmul_j_i = s[matmul].split(matmul_j, factor=8)
matmul_j_o_o_i, matmul_j_o_i = s[matmul].split(matmul_j_o_i, factor=2)
matmul_j_o_o_o, matmul_j_o_o_i = s[matmul].split(matmul_j_o_o_i, factor=32)
matmul_k_o, matmul_k_i = s[matmul].split(matmul_k, factor=32)
s[matmul].reorder(matmul_i_o_o_o, matmul_j_o_o_o, matmul_i_o_o_i, matmul_j_o_o_i, matmul_k_o, matmul_i_o_i, matmul_j_o_i, matmul_k_i, matmul_i_i, matmul_j_i)
out_i_o, out_i_i = s[out].split(out_i, factor=256)
out_j_o, out_j_i = s[out].split(out_j, factor=512)
s[out].reorder(out_i_o, out_j_o, out_i_i, out_j_i)
s[matmul].compute_at(s[out], out_j_o)
out_i_o_j_o_fused = s[out].fuse(out_i_o, out_j_o)
s[out].parallel(out_i_o_j_o_fused)
s[matmul].pragma(matmul_i_o_o_o, "auto_unroll_max_step", 64)
s[matmul].pragma(matmul_i_o_o_o, "unroll_explicit", True)
s[matmul].vectorize(matmul_j_i)
一个更复杂的例子是恢复搜索。在这种情况下，我们需要自己创建搜索策略和成本模型，并通过日志文件恢复搜索策略和成本模型（cost model）的状态。在下面的例子中，我们恢复了状态并做了更多的 5 次试验。
def resume_search(task, log_file):
print("Resume search:")
cost_model = auto_scheduler.XGBModel()
cost_model.update_from_file(log_file)
search_policy = auto_scheduler.SketchPolicy(
task, cost_model, init_search_callbacks=[auto_scheduler.PreloadMeasuredStates(log_file)]
)
tune_option = auto_scheduler.TuningOptions(
num_measure_trials=5, measure_callbacks=[auto_scheduler.RecordToFile(log_file)]
)
task.tune(tune_option, search_policy=search_policy)
resume_search(task, log_file)
输出结果如下：
