使用PyOpenCL进行结构对齐 [英] Struct Alignment with PyOpenCL
问题描述
更新:内核中的int4错误.
update: the int4 in my kernel was wrong.
我正在使用pyopencl，但是无法使结构对齐正常工作.在下面的代码(两次调用内核)中，正确返回了b值(为1)，但是c值具有一些随机"值.
I am using pyopencl but am unable to get struct alignment to work correctly. In the code below, which calls the kernel twice, the b value is returned correctly (as 1), but the c value has some "random" value.
换句话说: 我正在尝试读取结构的两个成员.我可以阅读第一个，但不能阅读第二个.为什么?
In other words: I am trying to read two members of a struct. I can read the first but not the second. Why?
无论我使用numpy结构化数组还是使用struct打包，都会发生相同的问题.而且注释中的_-attribute__设置也无济于事.
The same issue occurs whether I use numpy structured arrays or pack with struct. And the _-attribute__ settings in the comments don't help either.
我怀疑我在代码中的其他地方正在做一些愚蠢的操作，但是看不到它.任何帮助表示赞赏.
I suspect I am doing something stupid elsewhere in the code, but can't see it. Any help appreciated.
import struct as s
import pyopencl as cl
import numpy as n
ctx = cl.create_some_context()
queue = cl.CommandQueue(ctx)
for use_struct in (True, False):
if use_struct:
a = s.pack('=ii',1,2)
print(a, len(a))
a_dev = cl.Buffer(ctx, cl.mem_flags.WRITE_ONLY, len(a))
else:
# a = n.array([(1,2)], dtype=n.dtype('2i4', align=True))
a = n.array([(1,2)], dtype=n.dtype('2i4'))
print(a, a.itemsize, a.nbytes)
a_dev = cl.Buffer(ctx, cl.mem_flags.WRITE_ONLY, a.nbytes)
b = n.array([0], dtype='i4')
print(b, b.itemsize, b.nbytes)
b_dev = cl.Buffer(ctx, cl.mem_flags.READ_ONLY, b.nbytes)
c = n.array([0], dtype='i4')
print(c, c.itemsize, c.nbytes)
c_dev = cl.Buffer(ctx, cl.mem_flags.READ_ONLY, c.nbytes)
prg = cl.Program(ctx, """
typedef struct s {
int4 f0;
int4 f1 __attribute__ ((packed));
// int4 f1 __attribute__ ((aligned (4)));
// int4 f1;
} s;
__kernel void test(__global const s *a, __global int4 *b, __global int4 *c) {
*b = a->f0;
*c = a->f1;
}
""").build()
cl.enqueue_copy(queue, a_dev, a)
event = prg.test(queue, (1,), None, a_dev, b_dev, c_dev)
event.wait()
cl.enqueue_copy(queue, b, b_dev)
print(b)
cl.enqueue_copy(queue, c, c_dev)
print(c)
输出(我在剪切+粘贴时必须重新格式化，因此可能会稍微弄乱换行符；我还添加了注释，指示各种打印值是什么):
The output (I had to reformat while cut+pasting, so may have messed up line breaks slightly; I've also added comments indicating what the various print values are):
# first using struct
/home/andrew/projects/personal/kultrung/env/bin/python3.2 /home/andrew/projects/personal/kultrung/src/kultrung/test6.py
b'\x01\x00\x00\x00\x02\x00\x00\x00' 8 # the struct packed values
[0] 4 4 # output buffer 1
[0] 4 4 # output buffer 2
/home/andrew/projects/personal/kultrung/env/lib/python3.2/site-packages/pyopencl/cache.py:343: UserWarning: Build succeeded, but resulted in non-empty logs: Build on <pyopencl.Device 'Intel(R) Core(TM)2 CPU T5600 @ 1.83GHz' at 0x1385a20> succeeded, but said:
Build started Kernel <test> was successfully vectorized Done. warn("Build succeeded, but resulted in non-empty logs:\n"+message)
[1] # the first value (correct)
[240] # the second value (wrong)
# next using numpy
[[1 2]] 4 8 # the numpy struct
[0] 4 4 # output buffer
[0] 4 4 # output buffer
/home/andrew/projects/personal/kultrung/env/lib/python3.2/site-packages/pyopencl/__init__.py:174: UserWarning: Build succeeded, but resulted in non-empty logs: Build on <pyopencl.Device 'Intel(R) Core(TM)2 CPU T5600 @ 1.83GHz' at 0x1385a20> succeeded, but said:
Build started Kernel <test> was successfully vectorized Done. warn("Build succeeded, but resulted in non-empty logs:\n"+message)
[1] # first value (ok)
[67447488] # second value (wrong)
Process finished with exit code 0
推荐答案
好，我不知道我从哪里得到int4-我认为它必须是intel扩展名.使用int切换到AMD，因为内核类型按预期工作.我会在 http://acooke.org/cute/Somesimple0.html 上发布更多信息已经清理过了.
ok, i don't know where i got int4 from - i think it must be an intel extension. switching to AMD with int as the kernel type works as expected. i'll post more at http://acooke.org/cute/Somesimple0.html once i have cleaned things up.
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