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
151
152
153
| real cpu_reduction (GLuint src, size_t offset, size_t nb, const char op)
{
GL_C (glBindBuffer (GL_SHADER_STORAGE_BUFFER, src));
GL_C (glMemoryBarrier (GL_BUFFER_UPDATE_BARRIER_BIT));
real result = 0., * a = glMapBufferRange (GL_SHADER_STORAGE_BUFFER,
offset*sizeof(real), nb*sizeof(real),
GL_MAP_READ_BIT);
assert (a);
switch (op) {
case '+':
for (int i = 0; i < nb; i++, a++)
result += *a;
break;
case 'M':
result = *a++;
for (int i = 1; i < nb; i++, a++)
result = max (result, *a);
break;
case 'm':
result = *a++;
for (int i = 1; i < nb; i++, a++)
result = min (result, *a);
break;
default: assert (false);
}
assert (glUnmapBuffer (GL_SHADER_STORAGE_BUFFER));
GL_C (glBindBuffer (GL_SHADER_STORAGE_BUFFER, 0));
return result;
}
real gpu_reduction (size_t offset, const char op, const RegionParameters * region, size_t nb)
{
const int stride = 64, nwgr = 64;
bool is_foreach_point = (region->n.x == 1 && region->n.y == 1);
if (!is_foreach_point && nb < nwgr*stride)
return cpu_reduction (GPUContext.ssbo, offset, nb, op);
GLuint * br = gpu_grid->reduct;
if (!br[0]) {
GL_C (glGenBuffers (2, br));
for (int i = 0; i < 2; i++) {
GL_C (glBindBuffer (GL_SHADER_STORAGE_BUFFER, br[i]));
GL_C (glBufferData (GL_SHADER_STORAGE_BUFFER,
(sq(N + 1)/stride + 1)*sizeof(real),
NULL, GL_DYNAMIC_READ));
}
GL_C (glBindBuffer (GL_SHADER_STORAGE_BUFFER, 0));
}
const char * start, * operation;
static const char * startsum = "reduct = 0.;",
* opsum = "reduct += val;";
static const char * startmin = "reduct = val;",
* opmin = "if (val < reduct) reduct = val;";
static const char * startmax = "reduct = val;",
* opmax = "if (val > reduct) reduct = val;";
switch (op) {
case '+': start = startsum, operation = opsum; break;
case 'M': start = startmax, operation = opmax; break;
case 'm': start = startmin, operation = opmin; break;
default: // unknown reduction operation
assert (false);
}
char nwgrs[20], strides[20];
snprintf (nwgrs, 19, "%d", nwgr);
snprintf (strides, 19, "%d", stride);
char * fs =
str_append (NULL,
"#version 430\n", glsl_preproc,
"layout (std430, binding = 0) readonly buffer _data_layout {"
" real _data[]; };\n"
"layout (std430, binding = 1) writeonly buffer _reduct_layout {"
" real _reduct[]; };\n"
"layout (location = 3) uniform uint offset;\n"
"layout (location = 4) uniform uint nb;\n"
"layout (location = 5) uniform uint nbr;\n"
"layout (local_size_x = ", nwgrs, ") in;\n"
"void main() {\n"
"if (gl_GlobalInvocationID.x < nb) {\n"
" uint stride = ", strides, ";\n"
" uint index = stride*gl_GlobalInvocationID.x;\n"
" if (index + stride > nbr) stride = nbr - index;\n"
" index += offset;\n"
" real val = _data[index];\n"
" real ", start, "\n"
" for (uint j = 0; j < stride; j++) {\n"
" val = _data[index + j];\n"
" ", operation, "\n"
" }\n"
" _reduct[gl_GlobalInvocationID.x] = reduct;\n"
"}}\n");
Shader * shader;
Adler32Hash hash;
a32_hash_init (&hash);
a32_hash_add (&hash, fs, strlen (fs));
shader = load_shader (fs, a32_hash (&hash), NULL);
assert (shader);
if (shader->id != GPUContext.current_shader) {
GL_C (glUseProgram (shader->id));
GPUContext.current_shader = shader->id;
}
const GLint loffset = 3, lnb = 4, lnbr = 5;
if (is_foreach_point) {
real result = 0.;
int i = (region->p.x - X0)/L0*N;
int j = (region->p.y - Y0)/L0*N;
if (i >= 0 && i < N && j >= 0 && j < N) {
offset += i*N + j;
GL_C (glUniform1ui (loffset, offset));
GL_C (glBindBufferBase (GL_SHADER_STORAGE_BUFFER, 0, GPUContext.ssbo));
GL_C (glBindBufferBase (GL_SHADER_STORAGE_BUFFER, 1, br[0]));
GL_C (glUniform1ui (lnbr, 1));
GL_C (glUniform1ui (lnb, 1));
GL_C (glMemoryBarrier (GL_SHADER_STORAGE_BARRIER_BIT));
GL_C (glDispatchCompute (1, 1, 1));
GL_C (glBindBuffer (GL_SHADER_STORAGE_BUFFER, br[0]));
GL_C (glGetBufferSubData (GL_SHADER_STORAGE_BUFFER, 0, sizeof (real), &result));
GL_C (glBindBuffer (GL_SHADER_STORAGE_BUFFER, 0));
}
return result;
}
GL_C (glUniform1ui (loffset, offset));
GL_C (glBindBufferBase (GL_SHADER_STORAGE_BUFFER, 0, GPUContext.ssbo));
int src = 0, dst = 1;
while (nb >= nwgr*stride) {
GL_C (glBindBufferBase (GL_SHADER_STORAGE_BUFFER, 1, br[dst]));
GL_C (glUniform1ui (lnbr, nb));
if (nb % stride) {
nb /= stride;
nb++;
}
else
nb /= stride;
int ng = nb/nwgr;
if (ng*nwgr < nb)
ng++;
GL_C (glUniform1ui (lnb, nb));
GL_C (glMemoryBarrier (GL_SHADER_STORAGE_BARRIER_BIT));
GL_C (glDispatchCompute (ng, 1, 1));
swap (int, src, dst);
if (offset) {
GL_C (glUniform1ui (loffset, 0));
offset = 0;
}
GL_C (glBindBufferBase (GL_SHADER_STORAGE_BUFFER, 0, br[src]));
}
return cpu_reduction (br[src], 0, nb, op);
}
|
