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Merge pull request #4319 from ndtrung81/gpu_max_num_blocks

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Enable large numbers of atoms per proc with the GPU package
This commit is contained in:
Axel Kohlmeyer
2024-09-10 12:35:22 -04:00
committed by GitHub
parent b09e88a179 b16bb27184
commit 8e99835100
2 changed files with 24 additions and 7 deletions
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21
lib/gpu/lal_neighbor.cpp
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@ -586,8 +586,25 @@ void Neighbor::build_nbor_list(double **x, const int inum, const int host_inum,
const int b2y=_block_cell_2d;
const int g2x=static_cast<int>(ceil(static_cast<double>(_maxspecial)/b2x));
const int g2y=static_cast<int>(ceil(static_cast<double>(nt)/b2y));
_shared->k_transpose.set_size(g2x,g2y,b2x,b2y);
_shared->k_transpose.run(&dev_special,&dev_special_t,&_maxspecial,&nt);
// the maximum number of blocks on the device is typically 65535
// in principle we can use a lower number to have more resource per block 32768
const int max_num_blocks = 65535;
int shift = 0;
if (g2y < max_num_blocks) {
_shared->k_transpose.set_size(g2x,g2y,b2x,b2y);
_shared->k_transpose.run(&dev_special,&dev_special_t,&_maxspecial,&nt,&shift);
} else {
// using a fixed number of blocks
int g2y_m = max_num_blocks;
_shared->k_transpose.set_size(g2x,g2y_m,b2x,b2y);
// number of chunks needed for the whole transpose
const int num_chunks = ceil(static_cast<double>(g2y) / g2y_m);
for (int i = 0; i < num_chunks; i++) {
_shared->k_transpose.run(&dev_special,&dev_special_t,&_maxspecial,&nt,&shift);
shift += g2y_m*b2y;
}
}
time_transpose.stop();
}

10
lib/gpu/lal_neighbor_gpu.cu
View File

@ -147,7 +147,7 @@ __kernel void kernel_calc_cell_counts(const unsigned *restrict cell_id,
__kernel void transpose(__global tagint *restrict out,
const __global tagint *restrict in,
int columns_in, int rows_in)
int columns_in, int rows_in, int shift)
{
__local tagint block[BLOCK_CELL_2D][BLOCK_CELL_2D+1];
@ -158,15 +158,15 @@ __kernel void transpose(__global tagint *restrict out,
unsigned i=bi*BLOCK_CELL_2D+ti;
unsigned j=bj*BLOCK_CELL_2D+tj;
if ((i<columns_in) && (j<rows_in))
block[tj][ti]=in[j*columns_in+i];
if ((i<columns_in) && (j+shift<rows_in))
block[tj][ti]=in[(j+shift)*columns_in+i];
__syncthreads();
i=bj*BLOCK_CELL_2D+ti;
j=bi*BLOCK_CELL_2D+tj;
if ((i<rows_in) && (j<columns_in))
out[j*rows_in+i] = block[ti][tj];
if ((i+shift<rows_in) && (j<columns_in))
out[j*rows_in+i+shift] = block[ti][tj];
}
#ifndef LAL_USE_OLD_NEIGHBOR