Hi, I am having trouble with the basic usage of pyopencl. What is the
GLOBAL_SIZE parameter to the kernel calls? I can't seem to find a
description of this in the documentation. Perhaps it would help if anybody
knows where a few example programs could be found, outside of the three that
are included with the source?
Here's my failed attempt to multiply two square matrices:
import sys
import pyopencl as cl
from numpy import *
N = int(sys.argv[1])
precision = int(sys.argv[2])
m1 = random.rand(N,N).astype('float%s' % precision)
m2 = random.rand(N,N).astype('float%s' % precision)
print "m1:\n",m1
print "m2:\n",m2
ctx = cl.create_context_from_type(cl.device_type.ALL)
queue = cl.CommandQueue(ctx)
mf = cl.mem_flags
a_buf = cl.Buffer(ctx, mf.READ_ONLY | mf.COPY_HOST_PTR, hostbuf=m1)
b_buf = cl.Buffer(ctx, mf.READ_ONLY | mf.COPY_HOST_PTR, hostbuf=m2)
dest_buf = cl.Buffer(ctx, mf.WRITE_ONLY, m2.nbytes)
prg = cl.Program(ctx, """
__kernel void multwo(__global float *a,
__global float *b,
__global float *c)
{
int row = get_global_id(1);
int col = get_global_id(0);
float sum = 0.0f;
for (int i = 0; i < %d; i++) {
sum += a[row*%d+i] * b[i*%d+col];
}
c[row*%d+col] = sum;
}
"""%(N,N,N,N)).build()
prg.multwo(queue, (N,N), a_buf, b_buf, dest_buf)
product = zeros([N,N],dtype='float%s' % precision)
cl.enqueue_read_buffer(queue, dest_buf, product).wait()
print product
I get a bogus result:
[[ 1.21239019e+002 9.03297802e-315 0.00000000e+000]
[ 0.00000000e+000 0.00000000e+000 0.00000000e+000]
[ 0.00000000e+000 0.00000000e+000 0.00000000e+000]]
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