OpenMP

OpenMP OpenMP

1. OpenMP

1.1 OpenMP OpenMPOpenMP Fortran C/C++ www.openmp.org

OpenMP

OpenMP

IntelC++FortranMicrosoftVisual Studio 2005gcc4.2

1.2 OpenMP OpenMP OpenMPFork-JoinForkJoin

Fork-Join

OpenMP

OpenMP OpenMP C/C++OpenMP#pragma omp

Directiveparallel, for, parallel for, section, sections, single, master, critical, flush, ordered, atomic

OpenMPAPI omp.homp_get_thread_num()

,,,.,.,,

1.3 OpenMP Visual Studio .Net 2005OpenMP 2.0 /openmpOpenMP

OpenMP

#include "omp.h"

int _tmain(int argc, _TCHAR* argv[]){printf("Hello from serial.\n");printf("Thread number=%d\n",omp_get_thread_num());

#pragma omp parallel{printf("Hello from parallel. Thread number=%d\n", omp_get_thread_num());}printf("Hello from serial again.\n");

getchar();return 0;}

2. OpenMP

2.1 OpenMP C/C++ #pragma omp parallel for [clause[clause]]for i = first ; i

#pragma omp parallel [clause[clause]]{#pragma omp for [clause[clause]]for i = first ; i

for for index = start ; index < end ; increment_exprbreak gotoreturn continue

m

shareprivateschedule if ordered copyin

OpenMP OpenMP

threadprivate

sharedprivarefirstprivatelastprivate

parallel for Privatefirstprivatelastprivatereduction

# pragma omp parallel for privatearx,ary,n reduction+:a,bfori=0;i

OpenMPC/C++

firstprivate lastprivate

#pragma omp parallel for Data Race

2.2 #pragma omp parallel [clause[clause]]block

parallelparallel parallelbarrierjoin

threadprivate,copyinthreadprivate()copyin

threadprivate, copyin

#pragma omp parallel privatemyid{nthreads=omp_get_num_threads;myid=omp_get_thread_num;get_my_work_donemyid,nthreads;}

2.3 OpenMP

OpenMP criticalatomic

critical #pragma omp critical [name]blockblock

#pragma omp atomicx ++

OpenMPbarrierordered sectionsmaster

barrier #pragma omp for#pragma omp single #pragma omp sections nowait

#pragma omp barrier #pragma omp parallel{initialization;#pragma omp barrierprocess;}

ordered ordered

OpenMPOpenMPforCPU

int i, j;int a[100][100] = {0};for ( i =0; i < 100; i++){for( j = i; j < 100; j++ ){ a[i][j] = i*j;}} 425i0i99100

for scheduleschedule(type[,size])

type static dynamicguidedruntime ()size () sizesize

(static) parallel forschedulestaticntn/tsizen/t

#pragma omp parallel for schedule(static) for(i = 0; i < 10; i++ ) { printf("i=%d, thread_id=%d\n", i, omp_get_thread_num());}i=0, thread_id=0i=1, thread_id=0i=2, thread_id=0i=3, thread_id=0i=4, thread_id=0i=5, thread_id=1i=6, thread_id=1i=7, thread_id=1i=8, thread_id=1i=9, thread_id=1004159

#pragma omp parallel for schedule(static, 2) for(i = 0; i < 10; i++ ) { printf("i=%d, thread_id=%d\n", i, omp_get_thread_num());}i=0, thread_id=0i=1, thread_id=0i=4, thread_id=0i=5, thread_id=0i=8, thread_id=0i=9, thread_id=0i=2, thread_id=1i=3, thread_id=1i=6, thread_id=1i=7, thread_id=1010,2

(dynamic) sizesizesizesizesize

guidedguided guidedsizesize1

runtimerumtime runtimeOMP_SCHEDULE unixsetenvOMP_SCHEDULEsetenv OMP_SCHEDULEdynamic, 22windows||