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2026-07-13 12:36:30 +08:00

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#include <cuda.h>
#include <cuda_runtime.h>
#include <stdlib.h>
#include "common.h"
namespace gpu_easygraph {
static __device__ double atomicAddDouble (
_OUT_ double* address,
_IN_ double val
)
{
unsigned long long int* address_as_ull =
(unsigned long long int*)address;
unsigned long long int old = *address_as_ull, assumed;
do {
assumed = old;
old = atomicCAS(address_as_ull, assumed,
__double_as_longlong(val +
__longlong_as_double(assumed)));
} while (assumed != old);
return __longlong_as_double(old);
}
static __device__ double atomicMinDouble (
_OUT_ double *address,
_IN_ double val
)
{
unsigned long long ret = __double_as_longlong(*address);
while (val < __longlong_as_double(ret))
{
unsigned long long old = ret;
if ((ret = atomicCAS((unsigned long long *)address, old, __double_as_longlong(val))) == old)
break;
}
return __longlong_as_double(ret);
}
static __global__ void d_calc_min_edge (
_IN_ int* d_V,
_IN_ int* d_E,
_IN_ double* d_W,
_IN_ int len_V,
_IN_ int len_E,
_OUT_ double* d_min_edge
)
{
int tid = blockIdx.x * blockDim.x + threadIdx.x;
int tnum = blockDim.x * gridDim.x;
for (int u = tid; u < len_V; u += tnum) {
double curr_min = EG_DOUBLE_INF;
int edge_start = d_V[u];
int edge_end = d_V[u + 1];
for(int v = edge_start; v < edge_end; ++v) {
curr_min = min(curr_min, d_W[v]);
}
d_min_edge[u] = curr_min;
}
}
static __global__ void d_dijkstra_cc (
_IN_ int* d_V,
_IN_ int* d_E,
_IN_ double* d_W,
_IN_ double* d_min_edge,
_IN_ int* d_sources,
_BUFFER_ double* d_dist_2D,
_BUFFER_ int* d_U_2D,
_BUFFER_ int* d_F_2D,
_IN_ int len_V,
_IN_ int len_E,
_IN_ int len_sources,
_IN_ int warp_size,
_OUT_ double* d_CC
)
{
for (int s_idx = blockIdx.x; s_idx < len_sources; s_idx += gridDim.x) {
int s = d_sources[s_idx];
int* d_U = d_U_2D + blockIdx.x * len_V;
int* d_F = d_F_2D + blockIdx.x * len_V;
double* d_dist = d_dist_2D + blockIdx.x * len_V;
__shared__ int len_F;
__shared__ double delta;
__shared__ double dist_accum;
__shared__ int reachable_cnt;
for (int i = threadIdx.x; i < len_V; i += blockDim.x) {
d_U[i] = 1;
d_dist[i] = EG_DOUBLE_INF;
}
__syncthreads();
if (threadIdx.x == 0) {
d_dist[s] = 0.0;
d_F[0] = s;
len_F = 1;
delta = 0.0;
dist_accum = 0.0;
reachable_cnt = 0;
}
__syncthreads();
while (delta < EG_DOUBLE_INF) {
for (int j = threadIdx.x; j < len_F * warp_size; j += blockDim.x) {
int f = d_F[j / warp_size];
int edge_start = d_V[f];
int edge_end = d_V[f + 1];
double dist = d_dist[f];
for (int e = j % warp_size; e < edge_end - edge_start; e += warp_size) {
int adj = d_E[e + edge_start];
double relax_w = dist + d_W[e + edge_start];
atomicMinDouble(d_dist + adj, relax_w);
}
__threadfence_block();
}
__syncthreads();
if (threadIdx.x == 0) {
delta = EG_DOUBLE_INF;
}
__syncthreads();
for (int i = threadIdx.x; i < len_V; i += blockDim.x) {
double dist_i = d_dist[i];
if (d_U[i] == 1 && dist_i < EG_DOUBLE_INF) {
atomicMinDouble(&delta, dist_i + d_min_edge[i]);
}
}
__syncthreads();
if (threadIdx.x == 0) {
len_F = 0;
}
__syncthreads();
for (int i = threadIdx.x; i < len_V; i += blockDim.x) {
double dist_i = d_dist[i];
if (d_U[i] && dist_i <= delta && dist_i < EG_DOUBLE_INF) {
d_U[i] = 0;
int f_idx = atomicAdd(&len_F, 1);
d_F[f_idx] = i;
atomicAdd(&reachable_cnt, 1);
atomicAddDouble(&dist_accum, d_dist[i]);
}
}
__syncthreads();
}
if (threadIdx.x == 0) {
d_CC[s_idx] = dist_accum == 0.0 ? 0.0 :
(double)(reachable_cnt - 1) *
(double)(reachable_cnt - 1) /
((len_V - 1) * dist_accum);
}
__syncthreads();
}
}
// we here use CSR to represent a graph
int cuda_closeness_centrality (
_IN_ const int* V,
_IN_ const int* E,
_IN_ const double* W,
_IN_ const int* sources,
_IN_ int len_V,
_IN_ int len_E,
_IN_ int len_sources,
_IN_ int warp_size,
_OUT_ double* CC
)
{
int cuda_ret = cudaSuccess;
int EG_ret = EG_GPU_SUCC;
int min_edge_block_size;
int min_edge_grid_size;
int dijkstra_block_size;
int dijkstra_grid_size;
cudaOccupancyMaxPotentialBlockSize(&min_edge_grid_size, &min_edge_block_size, d_calc_min_edge, 0, 0);
cudaOccupancyMaxPotentialBlockSize(&dijkstra_grid_size, &dijkstra_block_size, d_dijkstra_cc, 0, 0);
int *d_V = NULL, *d_E = NULL, *d_sources= NULL;
int *d_U_2D = NULL, *d_F_2D = NULL;
double *d_W = NULL, *d_min_edge = NULL, *d_dist_2D = NULL, *d_CC = NULL;
EXIT_IF_CUDA_FAILED(cudaMalloc((void**)&d_V, sizeof(int) * (len_V + 1)));
EXIT_IF_CUDA_FAILED(cudaMalloc((void**)&d_E, sizeof(int) * len_E));
EXIT_IF_CUDA_FAILED(cudaMalloc((void**)&d_sources, sizeof(int) * len_sources));
EXIT_IF_CUDA_FAILED(cudaMalloc((void**)&d_U_2D, sizeof(int) * dijkstra_grid_size * len_V));
EXIT_IF_CUDA_FAILED(cudaMalloc((void**)&d_F_2D, sizeof(int) * dijkstra_grid_size * len_V));
EXIT_IF_CUDA_FAILED(cudaMalloc((void**)&d_W, sizeof(double) * len_E));
EXIT_IF_CUDA_FAILED(cudaMalloc((void**)&d_min_edge, sizeof(double) * len_V));
EXIT_IF_CUDA_FAILED(cudaMalloc((void**)&d_dist_2D, sizeof(double) * dijkstra_grid_size * len_V));
EXIT_IF_CUDA_FAILED(cudaMalloc((void**)&d_CC, sizeof(double) * len_V));
EXIT_IF_CUDA_FAILED(cudaMemcpy(d_V, V, sizeof(int) * (len_V + 1), cudaMemcpyHostToDevice));
EXIT_IF_CUDA_FAILED(cudaMemcpy(d_E, E, sizeof(int) * len_E, cudaMemcpyHostToDevice));
EXIT_IF_CUDA_FAILED(cudaMemcpy(d_sources, sources, sizeof(int) * len_sources, cudaMemcpyHostToDevice));
EXIT_IF_CUDA_FAILED(cudaMemcpy(d_W, W, sizeof(double) * len_E, cudaMemcpyHostToDevice));
d_calc_min_edge<<<dijkstra_grid_size, dijkstra_block_size>>>(d_V, d_E, d_W, len_V, len_E, d_min_edge);
d_dijkstra_cc<<<min_edge_grid_size, min_edge_block_size>>>(d_V, d_E, d_W, d_min_edge, d_sources,
d_dist_2D, d_U_2D, d_F_2D, len_V, len_E, len_sources, warp_size, d_CC);
EXIT_IF_CUDA_FAILED(cudaMemcpy(CC, d_CC, sizeof(double) * len_V, cudaMemcpyDeviceToHost));
exit:
cudaFree(d_V);
cudaFree(d_E);
cudaFree(d_sources);
cudaFree(d_U_2D);
cudaFree(d_F_2D);
cudaFree(d_W);
cudaFree(d_min_edge);
cudaFree(d_dist_2D);
cudaFree(d_CC);
if (cuda_ret != cudaSuccess) {
switch (cuda_ret) {
case cudaErrorMemoryAllocation:
EG_ret = EG_GPU_FAILED_TO_ALLOCATE_DEVICE_MEM;
break;
default:
EG_ret = EG_GPU_DEVICE_ERR;
break;
}
}
return EG_ret;
}
} // namespace gpu_easygraph