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
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
|
/* Copyright (c) 2022, NVIDIA CORPORATION. All rights reserved.
*
* Redistribution and use in source and binary forms, with or without
* modification, are permitted provided that the following conditions
* are met:
* * Redistributions of source code must retain the above copyright
* notice, this list of conditions and the following disclaimer.
* * Redistributions in binary form must reproduce the above copyright
* notice, this list of conditions and the following disclaimer in the
* documentation and/or other materials provided with the distribution.
* * Neither the name of NVIDIA CORPORATION nor the names of its
* contributors may be used to endorse or promote products derived
* from this software without specific prior written permission.
*
* THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS ``AS IS'' AND ANY
* EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
* IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR
* PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT OWNER OR
* CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL,
* EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO,
* PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR
* PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY
* OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
* (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
* OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
*/
#include "FDTD3dGPU.h"
#include <cooperative_groups.h>
namespace cg = cooperative_groups;
// Note: If you change the RADIUS, you should also change the unrolling below
#define RADIUS 4
__constant__ float stencil[RADIUS + 1];
__global__ void FiniteDifferencesKernel(float *output, const float *input,
const int dimx, const int dimy,
const int dimz) {
bool validr = true;
bool validw = true;
const int gtidx = blockIdx.x * blockDim.x + threadIdx.x;
const int gtidy = blockIdx.y * blockDim.y + threadIdx.y;
const int ltidx = threadIdx.x;
const int ltidy = threadIdx.y;
const int workx = blockDim.x;
const int worky = blockDim.y;
// Handle to thread block group
cg::thread_block cta = cg::this_thread_block();
__shared__ float tile[k_blockDimMaxY + 2 * RADIUS][k_blockDimX + 2 * RADIUS];
const int stride_y = dimx + 2 * RADIUS;
const int stride_z = stride_y * (dimy + 2 * RADIUS);
int inputIndex = 0;
int outputIndex = 0;
// Advance inputIndex to start of inner volume
inputIndex += RADIUS * stride_y + RADIUS;
// Advance inputIndex to target element
inputIndex += gtidy * stride_y + gtidx;
float infront[RADIUS];
float behind[RADIUS];
float current;
const int tx = ltidx + RADIUS;
const int ty = ltidy + RADIUS;
// Check in bounds
if ((gtidx >= dimx + RADIUS) || (gtidy >= dimy + RADIUS)) validr = false;
if ((gtidx >= dimx) || (gtidy >= dimy)) validw = false;
// Preload the "infront" and "behind" data
for (int i = RADIUS - 2; i >= 0; i--) {
if (validr) behind[i] = input[inputIndex];
inputIndex += stride_z;
}
if (validr) current = input[inputIndex];
outputIndex = inputIndex;
inputIndex += stride_z;
for (int i = 0; i < RADIUS; i++) {
if (validr) infront[i] = input[inputIndex];
inputIndex += stride_z;
}
// Step through the xy-planes
#pragma unroll 9
for (int iz = 0; iz < dimz; iz++) {
// Advance the slice (move the thread-front)
for (int i = RADIUS - 1; i > 0; i--) behind[i] = behind[i - 1];
behind[0] = current;
current = infront[0];
#pragma unroll 4
for (int i = 0; i < RADIUS - 1; i++) infront[i] = infront[i + 1];
if (validr) infront[RADIUS - 1] = input[inputIndex];
inputIndex += stride_z;
outputIndex += stride_z;
cg::sync(cta);
// Note that for the work items on the boundary of the problem, the
// supplied index when reading the halo (below) may wrap to the
// previous/next row or even the previous/next xy-plane. This is
// acceptable since a) we disable the output write for these work
// items and b) there is at least one xy-plane before/after the
// current plane, so the access will be within bounds.
// Update the data slice in the local tile
// Halo above & below
if (ltidy < RADIUS) {
tile[ltidy][tx] = input[outputIndex - RADIUS * stride_y];
tile[ltidy + worky + RADIUS][tx] = input[outputIndex + worky * stride_y];
}
// Halo left & right
if (ltidx < RADIUS) {
tile[ty][ltidx] = input[outputIndex - RADIUS];
tile[ty][ltidx + workx + RADIUS] = input[outputIndex + workx];
}
tile[ty][tx] = current;
cg::sync(cta);
// Compute the output value
float value = stencil[0] * current;
#pragma unroll 4
for (int i = 1; i <= RADIUS; i++) {
value +=
stencil[i] * (infront[i - 1] + behind[i - 1] + tile[ty - i][tx] +
tile[ty + i][tx] + tile[ty][tx - i] + tile[ty][tx + i]);
}
// Store the output value
if (validw) output[outputIndex] = value;
}
}
|
