将元素分配给数组不起作用（使用 OpenMP 并行合并排序）
[英]Assignment of an element to an array does not work (Parallel Mergesort with OpenMP)
问题描述
I want to parallelize mergesort.
我想并行化合并排序。 My idea was to look at the value in the middle of the first subarray and then perform a binary search on the other array to find an upper bound whose index should act as a pivot to split the second array there.Then I sort the first half of the first array with the first part of the second array sequentially and the second half of the first array with the second half of the second array.我的想法是查看第一个子数组中间的值，然后对另一个数组执行二分搜索以找到一个上限，其索引应作为枢轴在那里拆分第二个数组。然后我对前半部分进行排序第一个阵列的第一部分与第二个阵列的第一部分按顺序排列，第一个阵列的后半部分与第二个阵列的后半部分。 I want to uses tasks in open mp such that one thread performs the first merge and another thread performs the second merge.我想在 open mp 中使用任务，这样一个线程执行第一次合并，另一个线程执行第二次合并。
In my code the assignment cretes garbage values.在我的代码中，赋值产生了垃圾值。 Ie out[a]=in[b];即out[a]=in[b]; and then when I check printf("%d%",out[a]);然后当我检查printf("%d%",out[a]); I get a value c which is not in[b} .我得到一个不在in[b}的值c 。 When I print out the array the values out[i] sometimes differ from the value that were shown with the print function differ again, ie out[a]=d and d is neither c or in[b]当我打印出数组时，值out[i]有时与打印函数显示的值不同，即out[a]=d和d既不是c也不是in[b]
I have prepared the code and some output of some printstatements that show the values in[b] and in[a] .我已经准备了一些打印语句的代码和一些输出，这些语句显示了in[b]和in[a] 。
#include <stdio.h>
#include <stdlib.h>
#include <errno.h>
#include <sys/time.h>
#include <iostream>
#include <algorithm>
#include <cstdlib>
#include <cstdio>
#include <cmath>
#include <ctime>
#include <cstring>
#include <omp.h>
// Constants.h
#if !defined(MYLIB_CONSTANTS_H)
#define MYLIB_CONSTANTS_H 1
const int CUTOFF =11;
#endif
int binarysearchfinduperrank(int *in,int n,int value, int projection){
int* array= in+projection;
int L=0;
int R=n;
printf("\nUpperBinarysearchrankfinder [");
for(int i=0;i<n; i++){
printf("%d,",array[i]);
}
printf("]\n");
while(R-L>1){
int middle = (R+L)/2;
printf("L:%d,middle:%d,R:%d,value:%d\n",L,middle,R,value);
if(array[middle]==value){
while(array[middle]==value&&middle<n){
middle=middle+1;
}
printf("L:%d,R:%d,result:%d,index:%d\n",L,R,middle,middle+projection);
return middle;
}
if(array[middle]<value){
L=middle;
}
if(array[middle]>value){
R=middle;
}
}
printf("L:%d,R:%d,value:%d\n",L,R,value);
if(n==1){
if(array[0]> value){
printf(" result:0\n,index:%d\n",0+projection);
return 0;
}
else{
printf(" result:1,index:%d\n",1+projection);
return 1;
}
}
if(L==0&&array[L]>value){
printf("L:%d,R:%d,result:%d,index:%d\n",L,R,0,projection);
return 0;
}
if(R==n && array[R-1]<= value){
printf("L:%d,R:%d,result:%d,index:%d\n",L,R,n,n+projection);
return n;
}
if(R==n&& array[R-1]>value){
printf("L:%d,R:%d,result:%d,index:%d\n",L,R,R-1,((R-1)+projection));
return R-1;
}
if(array[R]<=value){
printf("L:%d,R:%d,result:%d,index:%d\n",L,R,R+1,(R+1+projection));
return R+1;
}
if(array[L]<=value){
printf("L:%d,R:%d,result:%d,index:%d\n",L,R,R,R+projection);
return R;
}
printf("L:%d,R:%d,result:%d,index:%d\n",L,R,L,L+projection);
return L;
}
void printarray(int *array,int n){
printf("\n[");
for(int i=0;i<n;i++){
printf("%d,",array[i]);
}
printf("]\n");
}
void MsMergeSequential(int *out, int *in, int begin1, int end1, int begin2, int end2, int outBegin) {
int left = begin1;
int right = begin2;
int idx = outBegin;
printf("Inputarray1:");
printarray(in+begin1,(end1-begin1));
printf("Inputarray2:");
printarray(in+begin2,(end2-begin2));
while (left < end1 && right < end2) {
if (in[left] <= in[right]) {
out[idx] = in[left];
printf("! %d \n",in[left]);
printf(" %d \n",out[idx]);
left++;
} else {
out[idx] = in[right];
printf("!! %d \n",in[left]);
printf(" %d \n",out[idx]);
right++;
}
idx++;
}
while (left < end1) {
out[idx] = in[left];
printf("!!! %d \n",in[left]);
printf(" %d \n",out[idx]);
left++, idx++;
}
while (right < end2) {
out[idx] = in[right];
printf(" !!!!%d \n",in[right]);
printf(" %d \n",out[idx]);
right++, idx++;
}
printf("Outputarray:\n[");
printarray(out+begin1,(end1-begin1)+(end2-begin2));
printf("]\n");
}
bool myfunc (long i , long j){return (i<j);}
void MsSequential(int *array, int *tmp, bool inplace, long begin, long end) {
if( end <= begin + CUTOFF -1){
std::sort(array+begin,array + end, myfunc);
}
else if (begin < (end - 1)) {
long half =(begin+end) / 2;
int halffirst= (half+begin)/2;
#pragma omp taskgroup
{
#pragma omp task shared(array) untied if(end-begin >= (1<<15))
MsSequential(array, tmp, !inplace, begin, half);
MsSequential(array, tmp, !inplace, half, end);
}
if (inplace){
printf("Originalinputarray-tmp:");
printarray(tmp+begin,(end-begin));
int halfsecond=binarysearchfinduperrank(tmp,(end-half),tmp[halffirst],half)+half+begin;
printf("%d,%d\n",halffirst,halfsecond);
printf("Halffirst:%d,Halfsecond:%d\n,",tmp[halffirst],tmp[halfsecond]);
#pragma omp taskgroup
{
#pragma omp task shared(tmp) untied if(end-begin >= (1<<15))
MsMergeSequential(array, tmp, begin, halffirst, half, halfsecond, begin);
MsMergeSequential(array, tmp, halffirst, half,halfsecond, end, begin+(halffirst-begin)+(halfsecond-half));
}
}
else {
int halfsecond=binarysearchfinduperrank(array,(end-half),array[halffirst],half)+half;
printf("%d,%d\n",halffirst,halfsecond);
printf("Originalinputarray-arr:");
printarray(array+begin,(end-begin));
printf("Halffirst:%d,Halfsecond:%d\n,",array[halffirst],array[halfsecond]);
#pragma omp taskgroup
{
#pragma omp task shared(array) untied if(end-begin >= (1<<15))
MsMergeSequential(tmp, array, begin, halffirst, half,halfsecond, begin);
MsMergeSequential(tmp, array, halffirst, half,halfsecond, end, begin+halffirst+(halfsecond-half));
}
}
} else if (!inplace) {
tmp[begin] = array[begin];
}
}
void MsParallel(int *array, int *tmp, const size_t size) {
MsSequential(array, tmp, true, 0, size);
}
bool isSorted(int ref[], int data[], const size_t size){
std::sort(ref, ref + size);
for (size_t idx = 0; idx < size; ++idx){
if (ref[idx] != data[idx]) {
printf("\nFalscher Index:%d\n",idx);
return false;
}
}
return true;
}
/**
/**
* @brief program entry point
*/
int main(int argc, char* argv[]) {
// variables to measure the elapsed time
struct timeval t1, t2;
double etime;
// expect one command line arguments: array size
if (argc != 2) {
printf("Usage: MergeSort.exe <array size> \n");
printf("\n");
return EXIT_FAILURE;
}
else {
const size_t stSize = strtol(argv[1], NULL, 10);
int *data = (int*) malloc(stSize * sizeof(int));
int *tmp = (int*) malloc(stSize * sizeof(int));
int *ref = (int*) malloc(stSize * sizeof(int));
printf("Initialization...\n");
srand(95);
#pragma omp parallel for num_threads(100) schedule(static)
{
for (size_t idx = 0; idx < stSize; ++idx){
data[idx] = (int) (stSize * (double(rand()) / RAND_MAX));
}
}
std::copy(data, data + stSize, ref);
double dSize = (stSize * sizeof(int)) / 1024 / 1024;
printf("Sorting %u elements of type int (%f MiB)...\n", stSize, dSize);
gettimeofday(&t1, NULL);
// Mergesort starts
#pragma omp parallel num_threads(80)
{
#pragma omp single
{
MsParallel(data, tmp, stSize);
}
}
gettimeofday(&t2, NULL);
etime = (t2.tv_sec - t1.tv_sec) * 1000 + (t2.tv_usec - t1.tv_usec) / 1000;
etime = etime / 1000;
printf("done, took %f sec. Verification...", etime);
if (isSorted(ref, data, stSize)) {
printf(" successful.\n");
}
else {
printf(" FAILED.\n");
}
free(data);
//delete[] data;
free(tmp);
//delete[] tmp;
free(ref);
//delete[] ref;
}
return EXIT_SUCCESS;
}
Output:(the ! marks are used to locate where the assignment in the code tool place)输出：（! 标记用于定位代码工具中赋值的位置）
Initialization...
Sorting 40 elements of type int (0.000000 MiB)...
UpperBinarysearchrankfinder [0,8,8,15,26,29,30,38,39,39,]
L:0,middle:5,R:10,value:15
L:0,middle:2,R:5,value:15
L:2,middle:3,R:5,value:15
L:2,R:5,result:4,index:14
5,14
Originalinputarray-arr:
[0,4,6,7,11,15,17,19,29,33,0,8,8,15,26,29,30,38,39,39,]
Halffirst:15,Halfsecond:26
,Inputarray1:
[0,4,6,7,11,]
Inputarray2:
[0,8,8,15,]
! 0
0
!! 4
0
! 4
4
! 6
6
! 7
7
!! 11
8
!! 11
8
! 11
11
!!!!15
15
Outputarray:
[
[0,0,4,6,7,8,8,11,15,]
]
Inputarray1:
[15,17,19,29,33,]
Inputarray2:
[26,29,30,38,39,39,]
! 15
15
! 17
17
! 19
19
!! 29
26
! 29
29
!! 33
29
!! 33
30
! 33
33
!!!!38
38
!!!!39
39
!!!!39
39
Outputarray:
[
[8,8,11,15,15,17,19,26,29,29,30,]
]
UpperBinarysearchrankfinder [1,5,7,11,16,26,27,30,32,36,]
L:0,middle:5,R:10,value:26
L:0,R:10,result:6,index:36
25,36
Originalinputarray-arr:
[3,4,5,7,10,26,29,33,34,35,1,5,7,11,16,26,27,30,32,36,]
Halffirst:26,Halfsecond:27
,Inputarray1:
[3,4,5,7,10,]
Inputarray2:
[1,5,7,11,16,26,]
!! 3
1
! 3
3
! 4
4
! 5
5
!! 7
5
! 7
7
!! 10
7
! 10
10
!!!!11
11
!!!!16
16
!!!!26
26
Outputarray:
[
[1,3,4,5,5,7,7,10,11,16,26,]
]
Inputarray1:
[26,29,33,34,35,]
Inputarray2:
[27,30,32,36,]
! 26
26
!! 29
27
! 29
29
!! 33
30
!! 33
32
! 33
33
! 34
34
! 35
35
!!!!36
36
Outputarray:
[
[7,7,10,11,16,26,-1751738988,-1684366952,-6382180,]
]
Originalinputarray-tmp:
[0,0,4,6,7,8,8,11,15,15,17,19,26,29,29,30,33,38,39,39,1,3,4,5,5,7,7,10,11,16,26,-1751738988,-1684366952,-6382180,-1549622880,-1482250844,-1414878808,-1347506772,-1280134736,-1212762700,]
UpperBinarysearchrankfinder [1,3,4,5,5,7,7,10,11,16,26,-1751738988,-1684366952,-6382180,-1549622880,-1482250844,-1414878808,-1347506772,-1280134736,-1212762700,]
L:0,middle:10,R:20,value:17
L:0,middle:5,R:10,value:17
L:5,middle:7,R:10,value:17
L:7,middle:8,R:10,value:17
L:8,middle:9,R:10,value:17
L:9,R:10,value:17
L:9,R:10,result:10,index:30
10,30
Halffirst:17,Halfsecond:26
,Inputarray1:
[0,0,4,6,7,8,8,11,15,15,]
Inputarray2:
[1,3,4,5,5,7,7,10,11,16,]
! 0
0
! 0
0
!! 4
1
!! 4
3
! 4
4
!! 6
4
!! 6
5
!! 6
5
! 6
6
! 7
7
!! 8
7
!! 8
7
! 8
8
! 8
8
!! 11
10
! 11
11
!! 15
11
! 15
15
! 15
15
!!!!16
16
Outputarray:
[
[0,0,1,3,4,4,5,5,6,7,7,7,8,8,10,11,11,15,15,16,]
]
Inputarray1:
[17,19,26,29,29,30,33,38,39,39,]
Inputarray2:
[26,-1751738988,-1684366952,-6382180,-1549622880,-1482250844,-1414878808,-1347506772,-1280134736,-1212762700,]
! 17
17
! 19
19
! 26
26
!! 29
26
!! 29
-1751738988
!! 29
-1684366952
!! 29
-6382180
!! 29
-1549622880
!! 29
-1482250844
!! 29
-1414878808
!! 29
-1347506772
!! 29
-1280134736
!! 29
-1212762700
!!! 29
29
!!! 29
29
!!! 30
30
!!! 33
33
!!! 38
38
!!! 39
39
!!! 39
39
Outputarray:
[
[7,7,8,8,10,11,11,15,15,16,17,19,26,26,-1751738988,-1684366952,-6382180,-1549622880,-1482250844,-1414878808,]
]
done, took 0.046000 sec. Verification...
Falscher Index:1
FAILED.
3 个解决方案
解决方案1
2 2021-07-24 20:20:28
If you want to parallelize it the you should use threads to do the sorting part in parallel.如果要并行化它，则应使用线程并行执行排序部分。 I don't see any parallelization in your code.我在您的代码中没有看到任何并行化。
The normal Mergesort is:正常的合并排序是：
mergesort(arr, l, r):
1. middle = (l + r)/2
2. mergesort(arr, l, middle)
3. mergesort(arr, middle + 1, r)
4. merge(arr, l, middle, r) //merges the subarray
If you wanna parallelize, you can create a thread to do 2 and another thread to do 3 and then join them, once they're done, you do the merge.如果你想并行化，你可以创建一个线程来做 2 和另一个线程来做 3 然后加入它们，一旦它们完成，你就进行合并。
mergesort(arr, l, r):
1. middle = (l + r)/2
2. create thread to execute mergesort(arr, l, middle)
3. create thread to execute mergesort(arr, middle + 1, r)
4. wait until both threads are done
5. merge(arr, l, middle, r) //merges the subarray
The time complexity is T(n) = T(n/2) + O(n) which if you solve will be n + n/2 + n/4 + ... 1 = O(n).时间复杂度为 T(n) = T(n/2) + O(n)，如果您求解，它将是 n + n/2 + n/4 + ... 1 = O(n)。
解决方案2
1 2021-07-24 21:13:22
I created a simplified sequential example of a top down merge sort using binary search for the merge.我创建了一个使用二进制搜索进行合并的自顶向下合并排序的简化顺序示例。 I verified that the code is a stable sort using a modified version.我使用修改后的版本验证了该代码是一种稳定的类型。 MergeSortAtoA and MergeSortAtoB are mutually recursive functions that call each other, instead of passing an inplace flag. MergeSortAtoA 和 MergeSortAtoB 是相互调用的相互递归函数，而不是传递一个就地标志。 The main point of this are the functions BinSrchLo, BinSrchHi, and Merge.其要点是函数 BinSrchLo、BinSrchHi 和 Merge。 BinSrchxx(a, ll, rr, v) returns the index where v would be inserted into a[ll,rr] (as if a[] is expanded by 1 element to make room for the inserted element). BinSrchxx(a, ll, rr, v) 返回将 v 插入到 a[ll,rr] 中的索引（就好像 a[] 扩展了 1 个元素以为插入的元素腾出空间）。 For example, if v < a[ll], it returns ll or if v > a[rr-1], it returns rr.例如，如果 v < a[ll]，则返回 ll；如果 v > a[rr-1]，则返回 rr。 Note that merge assigns b[i+j-rr] = a[i] in both for loops.请注意，merge 在两个 for 循环中都分配了 b[i+j-rr] = a[i]。 Check for differences between your code and this working example.检查您的代码与此工作示例之间的差异。
void MergeSortAtoA(int a[], int b[], size_t ll, size_t ee);
void MergeSortAtoB(int a[], int b[], size_t ll, size_t ee);
void Merge(int a[], int b[], size_t ll, size_t rr, size_t ee);
void MergeSort(int a[], int b[], size_t n)
{
MergeSortAtoA(a, b, 0, n);
}
void MergeSortAtoA(int a[], int b[], size_t ll, size_t ee)
{
if (ee-ll > 1) {
size_t rr = (ll + ee)>>1; /* midpoint, start of right half */
MergeSortAtoB(a, b, ll, rr);
MergeSortAtoB(a, b, rr, ee);
Merge(b, a, ll, rr, ee); /* merge b to a */
}
}
void MergeSortAtoB(int a[], int b[], size_t ll, size_t ee)
{
if (ee-ll > 1) {
size_t rr = (ll+ee)/2; /* midpoint, start of right half */
MergeSortAtoA(a, b, ll, rr);
MergeSortAtoA(a, b, rr, ee);
Merge(a, b, ll, rr, ee); /* merge a to b */
} else if (ee-ll == 1) {
b[ll] = a[ll];
}
}
size_t BinSrchLo(int a[], size_t ll, size_t rr, int v)
{
while(ll < rr){
size_t i = (ll+rr)/2;
if(a[i] < v)
ll = i+1;
else
rr = i;
}
return ll;
}
size_t BinSrchHi(int a[], size_t ll, size_t rr, int v)
{
while(ll < rr){
size_t i = (ll+rr)/2;
if(a[i] <= v)
ll = i+1;
else
rr = i;
}
return ll;
}
void Merge(uint64_t a[], uint64_t b[], size_t ll, size_t rr, size_t ee)
{
for(size_t i = ll; i < rr; i++){
size_t j = BinSrchLo(a, rr, ee, a[i]);
b[i+j-rr] = a[i];
}
for(size_t i = rr; i < ee; i++){
size_t j = BinSrchHi(a, ll, rr, a[i]);
b[i+j-rr] = a[i];
}
}
解决方案3
0 2021-07-25 18:33:53
There were some errors in the code so that the variable halffirst was not assigned to the index it was supposed to.代码中有一些错误，因此变量 halffirst 没有分配给它应该分配的索引。 And also the leaf arrays at the bottom were filled with garbagevalues.底部的叶子数组也充满了垃圾值。 The fixed code is here.固定代码在这里。 The runtime for an array of the size 10^7 is 0.2 seconds, and for an array of the size 10^8 2.4 seconds, assumed that the computer has 256 threads大小为 10^7 的数组的运行时间为 0.2 秒，大小为 10^8 的数组为 2.4 秒，假设计算机有 256 个线程
#include <stdio.h>
#include <stdlib.h>
#include <errno.h>
#include <sys/time.h>
#include <iostream>
#include <algorithm>
#include <cstdlib>
#include <cstdio>
#include <cmath>
#include <ctime>
#include <cstring>
#include <omp.h>
// Constants.h
#if !defined(MYLIB_CONSTANTS_H)
#define MYLIB_CONSTANTS_H 1
const int CUTOFF =11;
#endif
int binarysearchfinduperrank(int *in,int n,int value, int projection){
int* array= in+projection;
int L=0;
int R=n;
/*printf*/("\nUpperBinarysearchrankfinder [");
// for(int i=0;i<n; i++){
// printf("%d,",array[i]);
// }
// printf("]\n");
while(R-L>1){
int middle = (R+L)/2;
// printf("L:%d,middle:%d,R:%d,value:%d\n",L,middle,R,value);
if(array[middle]==value){
while(array[middle]==value&&middle<n){
middle=middle+1;
}
// printf("L:%d,R:%d,result:%d,index:%d\n",L,R,middle,middle+projection);
return middle;
}
if(array[middle]<value){
L=middle;
}
if(array[middle]>value){
R=middle;
}
}
// printf("L:%d,R:%d,value:%d\n",L,R,value);
if(n==1){
if(array[0]> value){
// printf(" result:0\n,index:%d\n",0+projection);
return 0;
}
else{
// printf(" result:1,index:%d\n",1+projection);
return 1;
}
}
if(L==0&&array[L]>value){
// printf("L:%d,R:%d,result:%d,index:%d\n",L,R,0,projection);
return 0;
}
if(R==n && array[R-1]<= value){
// printf("L:%d,R:%d,result:%d,index:%d\n",L,R,n,n+projection);
return n;
}
if(R==n&& array[R-1]>value){
// printf("L:%d,R:%d,result:%d,index:%d\n",L,R,R-1,((R-1)+projection));
return R-1;
}
if(array[R]<=value){
// printf("L:%d,R:%d,result:%d,index:%d\n",L,R,R+1,(R+1+projection));
return R+1;
}
if(array[L]<=value){
// printf("L:%d,R:%d,result:%d,index:%d\n",L,R,R,R+projection);
return R;
}
// printf("L:%d,R:%d,result:%d,index:%d\n",L,R,L,L+projection);
return L;
}
void printarray(int *array,int n){
printf("\n[");
for(int i=0;i<n;i++){
printf("%d,",array[i]);
}
printf("]\n");
}
void MsMergeSequential(int *out, int *in, int begin1, int end1, int begin2, int end2, int outBegin) {
int left = begin1;
int right = begin2;
int idx = outBegin;
// printf("Inputarray1:");
// printarray(in+begin1,(end1-begin1));
// printf("Inputarray2:");
// printarray(in+begin2,(end2-begin2));
while (left < end1 && right < end2) {
if (in[left] <= in[right]) {
out[idx] = in[left];
// printf("! %d \n",in[left]);
// printf(" %d \n",out[idx]);
left++;
} else {
out[idx] = in[right];
// printf("!! %d \n",in[left]);
// printf(" %d \n",out[idx]);
right++;
}
idx++;
}
while (left < end1) {
out[idx] = in[left];
// printf("!!! %d \n",in[left]);
// printf(" %d \n",out[idx]);
left++, idx++;
}
while (right < end2) {
out[idx] = in[right];
// printf(" !!!!%d \n",in[right]);
// printf(" %d \n",out[idx]);
right++, idx++;
}
// printf("Outputarray:\n[");
// printarray(out+outBegin,end2-outBegin);
// printf("]\n");
}
bool myfunc (long i , long j){return (i<j);}
void MsSequential(int *array, int *tmp, bool inplace, long begin, long end) {
if( end <= begin + CUTOFF -1){
std::sort(array+begin,array + end, myfunc);
std::copy(array+begin,array+end,tmp+begin);
}
else if (begin < (end - 1)) {
long half =(begin+end) / 2;
int halffirst= (half+begin)/2;
#pragma omp taskgroup
{
#pragma omp task shared(array) untied if(end-begin >= (1<<15))
MsSequential(array, tmp, !inplace, begin, half);
MsSequential(array, tmp, !inplace, half, end);
}
if (inplace){
// printf("Originalinputarray-tmp:");
// printarray(tmp+begin,(end-begin));
int halfsecond=binarysearchfinduperrank(tmp,(end-half),tmp[halffirst],half)+half;
// printf("%d,%d\n",halffirst,halfsecond);
// printf("Halffirst:%d,Halfsecond:%d\n,",tmp[halffirst],tmp[halfsecond]);
#pragma omp taskgroup
{
#pragma omp task shared(tmp) untied if(end-begin >= (1<<15))
MsMergeSequential(array, tmp, begin, halffirst, half, halfsecond, begin);
MsMergeSequential(array, tmp, halffirst, half,halfsecond, end, begin+(halffirst-begin)+(halfsecond-half));
}
}
else {
int halfsecond=binarysearchfinduperrank(array,(end-half),array[halffirst],half)+half;
// printf("%d,%d\n",halffirst,halfsecond);
// printf("Originalinputarray-arr:");
// printarray(array+begin,(end-begin));
// printf("Halffirst:%d,Halfsecond:%d\n,",array[halffirst],array[halfsecond]);
#pragma omp taskgroup
{
#pragma omp task shared(array) untied if(end-begin >= (1<<15))
MsMergeSequential(tmp, array, begin, halffirst, half,halfsecond, begin);
MsMergeSequential(tmp, array, halffirst, half,halfsecond, end, begin+(halffirst-begin)+(halfsecond-half));
}
}
} else if (!inplace) {
tmp[begin] = array[begin];
}
}
void MsParallel(int *array, int *tmp, const size_t size) {
MsSequential(array, tmp, true, 0, size);
}
bool isSorted(int ref[], int data[], const size_t size){
std::sort(ref, ref + size);
for (size_t idx = 0; idx < size; ++idx){
if (ref[idx] != data[idx]) {
// printf("\nFalscher Index:%d\n",idx);
return false;
}
}
return true;
}
/**
/**
* @brief program entry point
*/
int main(int argc, char* argv[]) {
// variables to measure the elapsed time
struct timeval t1, t2;
double etime;
// expect one command line arguments: array size
if (argc != 2) {
// printf("Usage: MergeSort.exe <array size> \n");
// printf("\n");
return EXIT_FAILURE;
}
else {
const size_t stSize = strtol(argv[1], NULL, 10);
int *data = (int*) malloc(stSize * sizeof(int));
int *tmp = (int*) malloc(stSize * sizeof(int));
int *ref = (int*) malloc(stSize * sizeof(int));
printf("Initialization...\n");
srand(95);
#pragma omp parallel for num_threads(100) schedule(static)
{
for (size_t idx = 0; idx < stSize; ++idx){
data[idx] = (int) (stSize * (double(rand()) / RAND_MAX));
}
}
std::copy(data, data + stSize, ref);
double dSize = (stSize * sizeof(int)) / 1024 / 1024;
printf("Sorting %u elements of type int (%f MiB)...\n", stSize, dSize);
gettimeofday(&t1, NULL);
// Mergesort starts
#pragma omp parallel num_threads(80)
{
#pragma omp single
{
MsParallel(data, tmp, stSize);
}
}
gettimeofday(&t2, NULL);
etime = (t2.tv_sec - t1.tv_sec) * 1000 + (t2.tv_usec - t1.tv_usec) / 1000;
etime = etime / 1000;
printf("done, took %f sec. Verification...", etime);
if (isSorted(ref, data, stSize)) {
printf(" successful.\n");
}
else {
printf(" FAILED.\n");
}
free(data);
//delete[] data;
free(tmp);
//delete[] tmp;
free(ref);
//delete[] ref;
}
return EXIT_SUCCESS;
}
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