75 lines
2.5 KiB
C++
75 lines
2.5 KiB
C++
#include <cstdio>
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#include <mpi.h>
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// 分析负载均衡的辅助程序
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int main(int argc, char *argv[]) {
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int id, p;
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MPI_Init(&argc, &argv);
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MPI_Comm_size(MPI_COMM_WORLD, &p);
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MPI_Comm_rank(MPI_COMM_WORLD, &id);
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int n = 100000;
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if (argc == 2) {
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n = atoi(argv[1]);
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}
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// 计算每个进程的工作量
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int workload = 0;
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for (int i = 2 + id; i <= n; i += p) {
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workload++;
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}
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// 收集所有进程的工作量
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int *workloads = nullptr;
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if (id == 0) {
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workloads = new int[p];
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}
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MPI_Gather(&workload, 1, MPI_INT, workloads, 1, MPI_INT, 0, MPI_COMM_WORLD);
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if (id == 0) {
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printf("\n=== 负载均衡分析 (N=%d, P=%d) ===\n", n, p);
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printf("进程号\t检查的数字数量\t分配的数字范围\n");
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printf("------------------------------------------------\n");
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int total = 0;
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for (int i = 0; i < p; i++) {
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int start = 2 + i;
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int end = n;
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int count = workloads[i];
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total += count;
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printf("%d\t%d\t\t", i, count);
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if (count <= 5) {
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printf("[");
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for (int j = 0; j < count && j < 3; j++) {
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printf("%d", start + j * p);
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if (j < count - 1 && j < 2) printf(", ");
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}
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if (count > 3) printf(", ...");
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printf("]\n");
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} else {
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int last = start + (count - 1) * p;
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printf("[%d, %d, ..., %d] (步长=%d)\n", start, start + p, last, p);
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}
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}
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printf("------------------------------------------------\n");
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printf("平均工作量: %d\n", total / p);
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printf("最大工作量: %d\n", workloads[0]);
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printf("最小工作量: %d\n", workloads[p-1]);
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printf("负载不均衡度: %.2f%%\n",
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100.0 * (workloads[0] - workloads[p-1]) / (double)workloads[0]);
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printf("\n");
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// 分析素数检测的计算成本
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printf("=== 计算成本分析 ===\n");
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printf("注意：小数字的素数检测快，大数字的素数检测慢！\n");
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printf("进程0检测的数字: 2, %d, %d, ... (小数字，检测快)\n", 2+p, 2+2*p);
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printf("进程%d检测的数字: %d, %d, %d, ... (大数字，检测慢)\n",
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p-1, 2+(p-1), 2+2*(p-1), 2+3*(p-1));
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printf("\n");
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delete[] workloads;
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}
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MPI_Finalize();
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return 0;
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}
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