<2022-05-07 周六>
pyopencl在windows上的安装及使用因为pyopencl在windows上安装和使用不是想象中的那么容易，所以还是需要记录一下。
我的环境Python 3.10.4，按照pip install pyopencl的提示，先后安装了numpy，wheel和mako，总之，提示缺啥安装啥，然后就不管在cmd，powershell还是在Developer Command Prompt for VS 2022中都没有安装成功pyopencl，一直提示：
src\wrap_cl.hpp(70): fatal error C1083: Cannot open include file: 'CL/cl.h': No such file or directory
最后在官网上找到了方法，从“Christoph Gohlke distributes binary wheels for PyOpenCL on Windows.”下载pyopencl-2022.1.3-cp310-cp310-win_amd64.whl解决：
PS D:\dnld> pip install .\pyopencl-2022.1.3-cp310-cp310-win_amd64.whl
这样就安装成功了。使用官网的例子测试一下：
#!/usr/bin/env python
import numpy as np
import pyopencl as cl
a_np = np.random.rand(50000).astype(np.float32)
b_np = np.random.rand(50000).astype(np.float32)
ctx = cl.create_some_context()
queue = cl.CommandQueue(ctx)
mf = cl.mem_flags
a_g = cl.Buffer(ctx, mf.READ_ONLY | mf.COPY_HOST_PTR, hostbuf=a_np)
b_g = cl.Buffer(ctx, mf.READ_ONLY | mf.COPY_HOST_PTR, hostbuf=b_np)
prg = cl.Program(ctx, """
__kernel void sum(
__global const float *a_g, __global const float *b_g, __global float *res_g)
{
int gid = get_global_id(0);
res_g[gid] = a_g[gid] + b_g[gid];
}
""").build()
res_g = cl.Buffer(ctx, mf.WRITE_ONLY, a_np.nbytes)
knl = prg.sum # Use this Kernel object for repeated calls
knl(queue, a_np.shape, None, a_g, b_g, res_g)
res_np = np.empty_like(a_np)
cl.enqueue_copy(queue, res_np, res_g)
# Check on CPU with Numpy:
print(res_np - (a_np + b_np))
print("res_np : ", res_np)
print("(a_np + b_np): ", (a_np + b_np))
print(np.linalg.norm(res_np - (a_np + b_np)))
assert np.allclose(res_np, a_np + b_np)
运行效果：
PS D:\demos\t_pyopencl\demo> python.exe .\demo.py
Choose platform:
[0] <pyopencl.Platform 'Intel(R) OpenCL' at 0x1c89caa1e40>
Choice [0]:
Choose device(s):
[0] <pyopencl.Device 'Intel(R) HD Graphics 530' on 'Intel(R) OpenCL' at 0x1c89cb07160>
[1] <pyopencl.Device 'Intel(R) Core(TM) i5-6500 CPU @ 3.20GHz' on 'Intel(R) OpenCL' at 0x1c89c33df60>
Choice, comma-separated [0]:
Set the environment variable PYOPENCL_CTX=':' to avoid being asked again.
C:\Users\ysouyno\AppData\Local\Programs\Python\Python310\lib\site-packages\pyopencl\__init__.py:270: CompilerWarning: Non-empty compiler output encountered. Set the environment variable PYOPENCL_COMPILER_OUTPUT=1 to see more.
warn("Non-empty compiler output encountered. Set the "
[0. 0. 0. ... 0. 0. 0.]
res_np : [1.3405421 0.803946 0.69187665 ... 0.9120757 0.5142325 0.5313911 ]
(a_np + b_np): [1.3405421 0.803946 0.69187665 ... 0.9120757 0.5142325 0.5313911 ]
0.0
PS D:\demos\t_pyopencl\demo>
这里主要说明下PYOPENCL_CTX的环境变量设置，powershell的输出如下：
PS D:\demos\t_pyopencl\demo> $env:PYOPENCL_COMPILER_OUTPUT=1
PS D:\demos\t_pyopencl\demo> $env:PYOPENCL_CTX='0:0'
PS D:\demos\t_pyopencl\demo> python.exe .\demo.py
C:\Users\ysouyno\AppData\Local\Programs\Python\Python310\lib\site-packages\pyopencl\__init__.py:268: CompilerWarning: Built kernel retrieved from cache. Original from-source build had warnings:
Build on <pyopencl.Device 'Intel(R) HD Graphics 530' on 'Intel(R) OpenCL' at 0x1f43640f230> succeeded, but said:
fcl build 1 succeeded.
bcl build succeeded.
warn(text, CompilerWarning)
[0. 0. 0. ... 0. 0. 0.]
res_np : [1.1701384 1.1061795 1.1798061 ... 0.99728197 0.5002522 1.80389 ]
(a_np + b_np): [1.1701384 1.1061795 1.1798061 ... 0.99728197 0.5002522 1.80389 ]
0.0
PS D:\demos\t_pyopencl\demo> $env:PYOPENCL_CTX='0:1'
PS D:\demos\t_pyopencl\demo> python.exe .\demo.py
C:\Users\ysouyno\AppData\Local\Programs\Python\Python310\lib\site-packages\pyopencl\__init__.py:268: CompilerWarning: Built kernel retrieved from cache. Original from-source build had warnings:
Build on <pyopencl.Device 'Intel(R) Core(TM) i5-6500 CPU @ 3.20GHz' on 'Intel(R) OpenCL' at 0x1a9cda3ade0> succeeded, but said:
Compilation started
Compilation done
Linking started
Linking done
Device build started
Device build done
Kernel <sum> was successfully vectorized (8)
Done.
warn(text, CompilerWarning)
C:\Users\ysouyno\AppData\Local\Programs\Python\Python310\lib\site-packages\pyopencl\__init__.py:268: CompilerWarning: From-binary build succeeded, but resulted in non-empty logs:
Build on <pyopencl.Device 'Intel(R) Core(TM) i5-6500 CPU @ 3.20GHz' on 'Intel(R) OpenCL' at 0x1a9cda3ade0> succeeded, but said:
Device build started
Device build done
Reload Program Binary Object.
warn(text, CompilerWarning)
[0. 0. 0. ... 0. 0. 0.]
res_np : [0.3848073 1.6682227 1.1773763 ... 0.801935 1.1112832 1.5165817]
(a_np + b_np): [0.3848073 1.6682227 1.1773763 ... 0.801935 1.1112832 1.5165817]
0.0
PS D:\demos\t_pyopencl\demo>
cmd的输出如下：
D:\demos\t_pyopencl\demo>set PYOPENCL_COMPILER_OUTPUT=1
D:\demos\t_pyopencl\demo>set PYOPENCL_CTX=0:0
D:\demos\t_pyopencl\demo>python demo.py
C:\Users\ysouyno\AppData\Local\Programs\Python\Python310\lib\site-packages\pyopencl\__init__.py:268: CompilerWarning: Built kernel retrieved from cache. Original from-source build had warnings:
Build on <pyopencl.Device 'Intel(R) HD Graphics 530' on 'Intel(R) OpenCL' at 0x1bc6e0b1250> succeeded, but said:
fcl build 1 succeeded.
bcl build succeeded.
warn(text, CompilerWarning)
[0. 0. 0. ... 0. 0. 0.]
res_np : [0.6949563 1.1166335 0.57082427 ... 1.3923297 1.2337677 1.4651983 ]
(a_np + b_np): [0.6949563 1.1166335 0.57082427 ... 1.3923297 1.2337677 1.4651983 ]
0.0
D:\demos\t_pyopencl\demo>set PYOPENCL_CTX=0:1
D:\demos\t_pyopencl\demo>python demo.py
C:\Users\ysouyno\AppData\Local\Programs\Python\Python310\lib\site-packages\pyopencl\__init__.py:268: CompilerWarning: Built kernel retrieved from cache. Original from-source build had warnings:
Build on <pyopencl.Device 'Intel(R) Core(TM) i5-6500 CPU @ 3.20GHz' on 'Intel(R) OpenCL' at 0x22c8a4e1b60> succeeded, but said:
Compilation started
Compilation done
Linking started
Linking done
Device build started
Device build done
Kernel <sum> was successfully vectorized (8)
Done.
warn(text, CompilerWarning)
C:\Users\ysouyno\AppData\Local\Programs\Python\Python310\lib\site-packages\pyopencl\__init__.py:268: CompilerWarning: From-binary build succeeded, but resulted in non-empty logs:
Build on <pyopencl.Device 'Intel(R) Core(TM) i5-6500 CPU @ 3.20GHz' on 'Intel(R) OpenCL' at 0x22c8a4e1b60> succeeded, but said:
Device build started
Device build done
Reload Program Binary Object.
warn(text, CompilerWarning)
[0. 0. 0. ... 0. 0. 0.]
res_np : [1.0808852 1.2096584 0.8938436 ... 0.35234842 0.3697133 0.88079625]
(a_np + b_np): [1.0808852 1.2096584 0.8938436 ... 0.35234842 0.3697133 0.88079625]
0.0
D:\demos\t_pyopencl\demo>
注意powershell和cmd的设置方法不一样：
| SHELL | ENV |
|---|---|
| powershell | $env:PYOPENCL_CTX=‘0:1’ |
| cmd | set PYOPENCL_CTX=0:1 |
:前0表示platform，:后1表示device。
为什么这个时候了还要去了解pyopencl的使用？因为python的代码更简洁，可以快速的测试kernel函数，减少开发周期，就像当年学习octave一样。