/usr/share/doc/python-pyopencl-doc/examples/demo-struct-reduce.py is in python-pyopencl-doc 2016.1+git20161130-1.
This file is owned by root:root, with mode 0o644.
The actual contents of the file can be viewed below.
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60 61 62 63 64 65 66 67 68 69 | from __future__ import absolute_import
import numpy as np
import pyopencl as cl
def make_collector_dtype(device):
dtype = np.dtype([
("cur_min", np.int32),
("cur_max", np.int32),
("pad", np.int32),
])
name = "minmax_collector"
from pyopencl.tools import get_or_register_dtype, match_dtype_to_c_struct
dtype, c_decl = match_dtype_to_c_struct(device, name, dtype)
dtype = get_or_register_dtype(name, dtype)
return dtype, c_decl
ctx = cl.create_some_context()
queue = cl.CommandQueue(ctx)
mmc_dtype, mmc_c_decl = make_collector_dtype(ctx.devices[0])
preamble = mmc_c_decl + r"""//CL//
minmax_collector mmc_neutral()
{
// FIXME: needs infinity literal in real use, ok here
minmax_collector result;
result.cur_min = 1<<30;
result.cur_max = -(1<<30);
return result;
}
minmax_collector mmc_from_scalar(float x)
{
minmax_collector result;
result.cur_min = x;
result.cur_max = x;
return result;
}
minmax_collector agg_mmc(minmax_collector a, minmax_collector b)
{
minmax_collector result = a;
if (b.cur_min < result.cur_min)
result.cur_min = b.cur_min;
if (b.cur_max > result.cur_max)
result.cur_max = b.cur_max;
return result;
}
"""
from pyopencl.clrandom import rand as clrand
a_gpu = clrand(queue, (20000,), dtype=np.int32, a=0, b=10**6)
a = a_gpu.get()
from pyopencl.reduction import ReductionKernel
red = ReductionKernel(ctx, mmc_dtype,
neutral="mmc_neutral()",
reduce_expr="agg_mmc(a, b)", map_expr="mmc_from_scalar(x[i])",
arguments="__global int *x", preamble=preamble)
minmax = red(a_gpu).get()
assert abs(minmax["cur_min"] - np.min(a)) < 1e-5
assert abs(minmax["cur_max"] - np.max(a)) < 1e-5
|