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
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
|
/* Copyright 2019-2020 Andrew Myers, Maxence Thevenet, Remi Lehe
* Weiqun Zhang
*
* This file is part of WarpX.
*
* License: BSD-3-Clause-LBNL
*/
#ifndef WARPX_PARTICLES_SORTING_SORTINGUTILS_H_
#define WARPX_PARTICLES_SORTING_SORTINGUTILS_H_
#include "Particles/WarpXParticleContainer.H"
#include <AMReX_Gpu.H>
#include <AMReX_Partition.H>
/** \brief Fill the elements of the input vector with consecutive integer,
* starting from 0
*
* \param[inout] v Vector of integers, to be filled by this routine
*/
void fillWithConsecutiveIntegers( amrex::Gpu::DeviceVector<long>& v )
{
#ifdef AMREX_USE_GPU
// On GPU: Use amrex
auto data = v.data();
auto N = v.size();
AMREX_FOR_1D( N, i, {data[i] = i;});
#else
// On CPU: Use std library
std::iota( v.begin(), v.end(), 0L );
#endif
}
/** \brief Find the indices that would reorder the elements of `predicate`
* so that the elements with non-zero value precede the other elements
*
* \tparam ForwardIterator An iterator that supports std::advance
* \param[in, out] index_begin Point to the beginning of the vector which is
* to be filled with these indices
* \param[in, out] index_end Point to the end of the vector which is
* to be filled with these indices
* \param[in] predicate that indicates the elements that need to be reordered first
*/
template< typename ForwardIterator >
ForwardIterator stablePartition(ForwardIterator const index_begin,
ForwardIterator const index_end,
amrex::Gpu::DeviceVector<int> const& predicate)
{
#ifdef AMREX_USE_GPU
// On GPU: Use amrex
int const* AMREX_RESTRICT predicate_ptr = predicate.dataPtr();
int N = static_cast<int>(std::distance(index_begin, index_end));
auto num_true = amrex::StablePartition(&(*index_begin), N,
[predicate_ptr] AMREX_GPU_DEVICE (long i) { return predicate_ptr[i]; });
ForwardIterator sep = index_begin;
std::advance(sep, num_true);
#else
// On CPU: Use std library
ForwardIterator const sep = std::stable_partition(
index_begin, index_end,
[&predicate](long i) { return predicate[i]; }
);
#endif
return sep;
}
/** \brief Return the number of elements between `first` and `last`
*
* \tparam ForwardIterator An iterator that supports std::distance
* \param[in] first Points to a position in a vector
* \param[in] last Points to another position in a vector
* \return The number of elements between `first` and `last`
*/
template< typename ForwardIterator >
int iteratorDistance(ForwardIterator const first,
ForwardIterator const last)
{
return std::distance( first, last );
}
/** \brief Functor that fills the elements of the particle array `inexflag`
* with the value of the spatial array `bmasks`, at the corresponding particle position.
*
* \param[in] pti Contains information on the particle positions
* \param[in] bmasks Spatial array, that contains a flag indicating
* whether each cell is part of the gathering/deposition buffers
* \param[out] inexflag Vector to be filled with the value of `bmasks`
* \param[in] geom Geometry object, necessary to locate particles within the array `bmasks`
*
*/
class fillBufferFlag
{
public:
fillBufferFlag( WarpXParIter const& pti, amrex::iMultiFab const* bmasks,
amrex::Gpu::DeviceVector<int>& inexflag,
amrex::Geometry const& geom ) {
// Extract simple structure that can be used directly on the GPU
m_particles = &(pti.GetArrayOfStructs()[0]);
m_buffer_mask = (*bmasks)[pti].array();
m_inexflag_ptr = inexflag.dataPtr();
m_domain = geom.Domain();
for (int idim=0; idim<AMREX_SPACEDIM; idim++) {
m_prob_lo[idim] = geom.ProbLo(idim);
m_inv_cell_size[idim] = geom.InvCellSize(idim);
}
}
AMREX_GPU_HOST_DEVICE AMREX_FORCE_INLINE
void operator()( const long i ) const {
// Select a particle
auto const& p = m_particles[i];
// Find the index of the cell where this particle is located
amrex::IntVect const iv = amrex::getParticleCell( p,
m_prob_lo, m_inv_cell_size, m_domain );
// Find the value of the buffer flag in this cell and
// store it at the corresponding particle position in the array `inexflag`
m_inexflag_ptr[i] = m_buffer_mask(iv);
}
private:
amrex::GpuArray<amrex::Real,AMREX_SPACEDIM> m_prob_lo;
amrex::GpuArray<amrex::Real,AMREX_SPACEDIM> m_inv_cell_size;
amrex::Box m_domain;
int* m_inexflag_ptr;
WarpXParticleContainer::ParticleType const* m_particles;
amrex::Array4<int const> m_buffer_mask;
};
/** \brief Functor that fills the elements of the particle array `inexflag`
* with the value of the spatial array `bmasks`, at the corresponding particle position.
*
* Contrary to `fillBufferFlag`, here this is done only for the particles that
* the last elements of `particle_indices` point to (from the element at
* index `start_index` in `particle_indices`, to the last element of `particle_indices`)
*
* \param[in] pti Contains information on the particle positions
* \param[in] bmasks Spatial array, that contains a flag indicating
* whether each cell is part of the gathering/deposition buffers
* \param[out] inexflag Vector to be filled with the value of `bmasks`
* \param[in] geom Geometry object, necessary to locate particles within the array `bmasks`
* \param[in] start_index Index that which elements start to be modified
*/
class fillBufferFlagRemainingParticles
{
public:
fillBufferFlagRemainingParticles(
WarpXParIter const& pti,
amrex::iMultiFab const* bmasks,
amrex::Gpu::DeviceVector<int>& inexflag,
amrex::Geometry const& geom,
amrex::Gpu::DeviceVector<long> const& particle_indices,
long const start_index ) :
m_start_index(start_index) {
// Extract simple structure that can be used directly on the GPU
m_particles = &(pti.GetArrayOfStructs()[0]);
m_buffer_mask = (*bmasks)[pti].array();
m_inexflag_ptr = inexflag.dataPtr();
m_indices_ptr = particle_indices.dataPtr();
m_domain = geom.Domain();
for (int idim=0; idim<AMREX_SPACEDIM; idim++) {
m_prob_lo[idim] = geom.ProbLo(idim);
m_inv_cell_size[idim] = geom.InvCellSize(idim);
}
}
AMREX_GPU_HOST_DEVICE AMREX_FORCE_INLINE
void operator()( const long i ) const {
// Select a particle
auto const& p = m_particles[m_indices_ptr[i+m_start_index]];
// Find the index of the cell where this particle is located
amrex::IntVect const iv = amrex::getParticleCell( p,
m_prob_lo, m_inv_cell_size, m_domain );
// Find the value of the buffer flag in this cell and
// store it at the corresponding particle position in the array `inexflag`
m_inexflag_ptr[m_indices_ptr[i+m_start_index]] = m_buffer_mask(iv);
}
private:
amrex::GpuArray<amrex::Real,AMREX_SPACEDIM> m_prob_lo;
amrex::GpuArray<amrex::Real,AMREX_SPACEDIM> m_inv_cell_size;
amrex::Box m_domain;
int* m_inexflag_ptr;
WarpXParticleContainer::ParticleType const* m_particles;
amrex::Array4<int const> m_buffer_mask;
long const m_start_index;
long const* m_indices_ptr;
};
/** \brief Functor that copies the elements of `src` into `dst`,
* while reordering them according to `indices`
*
* \param[in] src Source vector
* \param[out] dst Destination vector
* \param[in] indices Array of indices that indicate how to reorder elements
*/
template <typename T>
class copyAndReorder
{
public:
copyAndReorder(
amrex::Gpu::DeviceVector<T> const& src,
amrex::Gpu::DeviceVector<T>& dst,
amrex::Gpu::DeviceVector<long> const& indices ) {
// Extract simple structure that can be used directly on the GPU
m_src_ptr = src.dataPtr();
m_dst_ptr = dst.dataPtr();
m_indices_ptr = indices.dataPtr();
}
AMREX_GPU_DEVICE AMREX_FORCE_INLINE
void operator()( const long ip ) const {
m_dst_ptr[ip] = m_src_ptr[ m_indices_ptr[ip] ];
}
private:
T const* m_src_ptr;
T* m_dst_ptr;
long const* m_indices_ptr;
};
#endif // WARPX_PARTICLES_SORTING_SORTINGUTILS_H_
|
