3.1.8.3.7.3. OpenMP¶
シングルノードジョブ(OpenMP)のCプログラムをコンパイルする例を示します。
- ソースプログラムを用意します。サンプルプログラムを
/home/system/sample/C/openmp/trad_sample_omp.c
として用意しています。
1#include <stdio.h>
2#include <math.h>
3#include <sys/time.h>
4
5#define N 5888
6
7double gettimeofday_sec(){
8 struct timeval tv;
9 gettimeofday(&tv, NULL);
10 return tv.tv_sec + (double)tv.tv_usec*1e-6;
11}
12
13int main(){
14 double a[N][N+1];
15 double b[N][N+1];
16 double c[N][N+1];
17 int i, j, k;
18 double t1,t2;
19
20//
21// print message
22//
23 printf ("\n");
24 printf ("%d, %d\n", N, N);
25
26//
27// initialize matrix
28//
29#pragma omp parallel for shared(a,b,c)
30 for (j = 0; j < N; j++) {
31 for (i = 0; i < N; i++) {
32 a[j][i] = 0.1;
33 b[j][i] = 0.3;
34 c[j][i] = 0.0;
35 }
36 }
37
38//
39// do matrix multiply
40//
41 t1 = gettimeofday_sec();
42#pragma omp parallel for shared(a,b,c)
43 for (j = 0; j < N; j++) {
44 for (i = 0; i < N; i++) {
45 for (k = 0; k < N; k++) {
46 c[i][j] = c[i][j] + a[i][k] * b[k][j];
47 }
48 }
49 }
50 t2 = gettimeofday_sec();
51
52//
53// print result
54//
55 printf("c[1][1] = %f\n", c[1][1]);
56 printf("time : %f sec.\n", t2 - t1);
57 return 0;
58}
サンプルプログラムをコンパイルします。
[_LNlogin]$ fccpx -V -Kfast,openmp,optmsg=2 -o sample_omp trad_sample_omp.c fccpx: Fujitsu C/C++ Compiler 4.1.0 simulating gcc version 6.1 ccpcompx: Fujitsu C/C++ Compiler 4.1.0 (Dec 19 2019 16:14:08) Optimization messages jwd6001s-i "trad_sample_omp.c", line 31: SIMD conversion is applied to this loop with the loop variable 'i'. jwd8663o-i "trad_sample_omp.c", line 31: This loop is not software pipelined because the software pipelining does not improve the performance. jwd8202o-i "trad_sample_omp.c", line 31: Loop unrolling expanding 2 times is applied to this loop. jwd8101o-i "trad_sample_omp.c", line 41: Inline expansion is applied to the user defined function 'gettimeofday_sec'. jwd8220o-i "trad_sample_omp.c", line 43: Optimizations that may cause side effect are applied. jwd8331o-i "trad_sample_omp.c", line 43: This loop is changed to the matmul library function call. jwd8101o-i "trad_sample_omp.c", line 50: Inline expansion is applied to the user defined function 'gettimeofday_sec'. GNU assembler version 2.30 (aarch64-linux-gnu) using BFD version version 2.30-49.el7 GNU ld version 2.30-49.el7 Supported emulations: aarch64linux aarch64elf aarch64elf32 aarch64elf32b aarch64elfb armelf armelfb aarch64linuxb aarch64linux32 aarch64linux32b armelfb_linux_eabi armelf_linux_eabi i386pep i386pe
- ジョブスクリプトを用意します。ジョブスクリプトのサンプルは
/home/system/sample/C/openmp/trad_job_openmp.sh
として用意しています。
#!/bin/sh #PJM -L "node=1" #PJM -L "rscgrp=small" #PJM -L "elapse=10:00" #PJM -x PJM_LLIO_GFSCACHE=/vol000N #PJM -g groupname #PJM -s # execute job export OMP_NUM_THREADS=12 ./sample_omp
pjsubコマンドでジョブを投入します。
[_LNlogin]$ pjsub trad_job_openmp.sh [INFO] PJM 0000 pjsub Job 117 submitted.
- 実行結果を確認します。標準出力は
ジョブ名.ジョブID.out
として出力されます。
[_LNlogin]$ cat trad_job_openmp.sh.117.out 5888, 5888 c[1][1] = 176.640000 time : 10.873365 sec.