├── .img
    └── alipay_jd_t.png
├── 00_dep
    ├── Makefile
    └── main.cpp
├── 01_parallel_cout
    ├── Makefile
    └── main.cpp
├── 02_parallel_no_omp
    ├── Makefile
    └── main.cpp
├── 03_reduce
    ├── Makefile
    └── main.cpp
├── 04_get_idx
    ├── Makefile
    └── main.cpp
├── 05_atomic_barrier
    ├── Makefile
    └── main.cpp
├── 06_mix
    ├── Makefile
    └── main.cpp
├── LICENSE
└── README.md


/.img/alipay_jd_t.png:
--------------------------------------------------------------------------------
https://raw.githubusercontent.com/tlqtangok/openmp_demo/a9c992b3896e25b7d7676c91551f8902d2d9e5e5/.img/alipay_jd_t.png


--------------------------------------------------------------------------------
/00_dep/Makefile:
--------------------------------------------------------------------------------
 1 | CC = g++ -std=c++11 
 2 | 
 3 | nullstring := 
 4 | dep_I_incpath = -I./include/hiredis -I./include
 5 | dep_L_libpath = -L./lib
 6 | dep_l_libname = -lhiredis
 7 | #deps_extra = $(dep_I_incpath) $(dep_L_libpath)  $(dep_l_libname)
 8 | 
 9 | deps_extra = $(nullstring)
10 | 
11 | #c_flag = -g -Wno-format -fpermissive 
12 | c_flag = -g -pthread -Wno-format -fpermissive -fopenmp
13 | 
14 | c_files =  \
15 | $(wildcard *.cpp) $(wildcard *.c) $(wildcard *.cc)
16 | h_files = \
17 | $(wildcard *.hpp) $(wildcard *.h)
18 | o_files_mess = \
19 | $(patsubst %.cpp,%.o,${c_files}) $(patsubst %.c,%.o,${c_files}) $(patsubst %.cc,%.o,${c_files})
20 | o_files = \
21 | $(filter %.o, $(o_files_mess))
22 | elf_file=  \
23 | mainapp.exe
24 | 
25 | rm_files = \
26 | *.o *.dep *.elf  *.s *.exe
27 | 
28 | 
29 | all:$(elf_file)
30 | 
31 | $(elf_file):$(o_files)
32 | 	$(CC) $(c_flag) -o $@ $(o_files) $(deps_extra) 
33 | main.o: main.cpp
34 | 	$(CC) $(c_flag) -o $@ -c $< $(deps_extra) 
35 | #	@echo "c_file is:$(c_files)"; echo "h_files:$(h_files)"; echo "o_files:$(o_files)"
36 | 
37 | clean:
38 | 	rm -rf $(rm_files)
39 | 
40 | run:$(elf_file)
41 | 	./$(elf_file)
42 | 
43 | 


--------------------------------------------------------------------------------
/00_dep/main.cpp:
--------------------------------------------------------------------------------
 1 | #include <iostream>
 2 | using namespace std; 
 3 | 
 4 | int main()
 5 | {
 6 | 
 7 | #if _OPENMP
 8 | 	cout << " support openmp " << endl; 
 9 | #else
10 | 	cout << " not support openmp" << endl; 
11 | #endif
12 | 	return 0; 
13 | }
14 | 


--------------------------------------------------------------------------------
/01_parallel_cout/Makefile:
--------------------------------------------------------------------------------
 1 | CC = g++ -std=c++11 
 2 | 
 3 | nullstring := 
 4 | dep_I_incpath = -I./include/hiredis -I./include
 5 | dep_L_libpath = -L./lib
 6 | dep_l_libname = -lhiredis
 7 | #deps_extra = $(dep_I_incpath) $(dep_L_libpath)  $(dep_l_libname)
 8 | 
 9 | deps_extra = $(nullstring)
10 | 
11 | #c_flag = -g -Wno-format -fpermissive 
12 | c_flag = -g -pthread -Wno-format -fpermissive -fopenmp
13 | 
14 | c_files =  \
15 | $(wildcard *.cpp) $(wildcard *.c) $(wildcard *.cc)
16 | h_files = \
17 | $(wildcard *.hpp) $(wildcard *.h)
18 | o_files_mess = \
19 | $(patsubst %.cpp,%.o,${c_files}) $(patsubst %.c,%.o,${c_files}) $(patsubst %.cc,%.o,${c_files})
20 | o_files = \
21 | $(filter %.o, $(o_files_mess))
22 | elf_file=  \
23 | mainapp.exe
24 | 
25 | rm_files = \
26 | *.o *.dep *.elf  *.s *.exe
27 | 
28 | 
29 | all:$(elf_file)
30 | 
31 | $(elf_file):$(o_files)
32 | 	$(CC) $(c_flag) -o $@ $(o_files) $(deps_extra) 
33 | main.o: main.cpp
34 | 	$(CC) $(c_flag) -o $@ -c $< $(deps_extra) 
35 | #	@echo "c_file is:$(c_files)"; echo "h_files:$(h_files)"; echo "o_files:$(o_files)"
36 | 
37 | clean:
38 | 	rm -rf $(rm_files)
39 | 
40 | run:$(elf_file)
41 | 	./$(elf_file)
42 | 
43 | 


--------------------------------------------------------------------------------
/01_parallel_cout/main.cpp:
--------------------------------------------------------------------------------
 1 | #include <iostream>
 2 | #include <omp.h>
 3 | 
 4 | using namespace std; 
 5 | 
 6 | int main()
 7 | {
 8 | 
 9 | 	#pragma omp parallel for num_threads(4)
10 | 	for(int i=0; i<10; i++)
11 | 	{
12 | 	cout << i << endl; 
13 | 	}
14 | 	return 0; 
15 | }
16 | 


--------------------------------------------------------------------------------
/02_parallel_no_omp/Makefile:
--------------------------------------------------------------------------------
 1 | CC = g++ -std=c++11 
 2 | 
 3 | nullstring := 
 4 | dep_I_incpath = -I./include/hiredis -I./include
 5 | dep_L_libpath = -L./lib
 6 | dep_l_libname = -lhiredis
 7 | #deps_extra = $(dep_I_incpath) $(dep_L_libpath)  $(dep_l_libname)
 8 | 
 9 | deps_extra = $(nullstring)
10 | 
11 | #c_flag = -g -Wno-format -fpermissive 
12 | c_flag = -g -pthread -Wno-format -fpermissive -fopenmp
13 | 
14 | c_files =  \
15 | $(wildcard *.cpp) $(wildcard *.c) $(wildcard *.cc)
16 | h_files = \
17 | $(wildcard *.hpp) $(wildcard *.h)
18 | o_files_mess = \
19 | $(patsubst %.cpp,%.o,${c_files}) $(patsubst %.c,%.o,${c_files}) $(patsubst %.cc,%.o,${c_files})
20 | o_files = \
21 | $(filter %.o, $(o_files_mess))
22 | elf_file=  \
23 | mainapp.exe
24 | 
25 | rm_files = \
26 | *.o *.dep *.elf  *.s *.exe
27 | 
28 | 
29 | all:$(elf_file)
30 | 
31 | $(elf_file):$(o_files)
32 | 	$(CC) $(c_flag) -o $@ $(o_files) $(deps_extra) 
33 | main.o: main.cpp
34 | 	$(CC) $(c_flag) -o $@ -c $< $(deps_extra) 
35 | #	@echo "c_file is:$(c_files)"; echo "h_files:$(h_files)"; echo "o_files:$(o_files)"
36 | 
37 | clean:
38 | 	rm -rf $(rm_files)
39 | 
40 | run:$(elf_file)
41 | 	./$(elf_file)
42 | 
43 | 


--------------------------------------------------------------------------------
/02_parallel_no_omp/main.cpp:
--------------------------------------------------------------------------------
  1 | #include <iostream>
  2 | //#include <omp.h>
  3 | #include <vector>
  4 | #include <cmath>
  5 | #include <thread>
  6 | 
  7 | 
  8 | using namespace std; 
  9 | 
 10 | template <class T>
 11 | void exec_e(T &e)
 12 | {
 13 | 	cout << e << endl;  
 14 | }
 15 | 
 16 | 
 17 | 
 18 | template <class T>
 19 | void exec_multi_threads_on_data(vector<T>& arr_src, const int& N, const int& td_num, void (*cb)(T &e))
 20 | {
 21 | 
 22 | #define FLAG_USE_MULTIPLE_THREAD_ 1 
 23 | 
 24 | #define FLAG_USE_SINGLE_THREAD_ (!FLAG_USE_MULTIPLE_THREAD_) 
 25 | 
 26 | 
 27 | 	//typedef  pair<int, std::thread> i_td;
 28 | 	//int td_num_real = td_num - 1; 
 29 | 	int mod_num = ceil (N * 1.0f / td_num );
 30 | 	vector< pair<int, std::thread> > arr_pair_i_td{};
 31 | 
 32 | 	arr_pair_i_td.resize(td_num);
 33 | 
 34 | 	//arr_pair_i_td.resize(N % mod_num == 0 ? N / mod_num : N / mod_num + 1);
 35 | 
 36 | 	int cnt = 0;
 37 | 	int cnt_arr = 0;
 38 | 
 39 | 	cnt = 0;
 40 | 	int flag_break_at_pad = 0;
 41 | 	int cnt_threads = 0; 
 42 | 	for(int i=0;i<td_num;i++)
 43 | 	{
 44 | 		auto id_td = i; 
 45 | 		int start ; 
 46 | 		int end; 
 47 | 		if(i*mod_num + mod_num <= N)
 48 | 		{
 49 | 			end = i * mod_num + mod_num; 
 50 | 		}
 51 | 		else
 52 | 		{
 53 | 			int pad_num = N % mod_num; 
 54 | 			end = i * mod_num + pad_num; 
 55 | 			flag_break_at_pad = 1; 
 56 | 		}
 57 | 		start = i * mod_num; 
 58 | 
 59 | 
 60 | 		cnt_threads++; 
 61 | 		auto pair_i_i = make_pair(start, end);
 62 | 		//auto pair_i_i = make_pair(cnt, cnt + mod_num > N ? N : cnt + mod_num);
 63 | 
 64 | 
 65 | 		arr_pair_i_td[id_td].first = id_td;
 66 | 		arr_pair_i_td[id_td].second = thread([&cb](int id_td, vector<T>& arr_src, pair<int, int> pair_i_i) {
 67 | #if 0 
 68 | 				float sleep_time_seconds = id_td * 0.02f;
 69 | 				string cmd_sleep = string("sleep ") + tools_to_string(sleep_time_seconds) + "s";
 70 | 				system(cmd_sleep.c_str());
 71 | 				//cout << cmd_sleep << endl; 
 72 | #endif 
 73 | 				//cout << "- id_td: " << id_td << endl;
 74 | 
 75 | 				for (auto i = pair_i_i.first; i < pair_i_i.second; i++)
 76 | 				{
 77 | 				//cout << arr_src[i] << " ";
 78 | 				cb(arr_src[i]);
 79 | 				}
 80 | 				//cout << endl << "--------------------" << endl;
 81 | 
 82 | 				},
 83 | 				id_td, std::ref(arr_src), pair_i_i
 84 | 				);
 85 | 
 86 | 
 87 | 
 88 | 
 89 | 
 90 | #if FLAG_USE_SINGLE_THREAD_
 91 | 		cout << "- FLAG_USE_SINGLE_THREAD_ " << endl; 
 92 | 		arr_pair_i_td[id_td].second.join();
 93 | #endif 
 94 | 
 95 | 		if (flag_break_at_pad) break; 
 96 | 	}
 97 | 
 98 | //cout << "- cnt_threads : " << cnt_threads << endl; 
 99 | 
100 | #if FLAG_USE_MULTIPLE_THREAD_  
101 | 	for (auto& e_pair : arr_pair_i_td)
102 | 	{
103 | 		e_pair.second.join();
104 | 	}
105 | 
106 | #endif
107 | 
108 | 
109 | 	arr_pair_i_td.clear();
110 | 
111 | 
112 | }
113 | 
114 | 
115 | 
116 | int main()
117 | {
118 | 
119 | 	const int N = 10;
120 | 	const int td_num = 3; 
121 | 
122 | 
123 | 	vector<int> arr_src{};
124 | 	arr_src.resize(N);
125 | 	int  cnt = 0;
126 | 	for (auto &e : arr_src)
127 | 	{
128 | 		e = cnt;
129 | 		cnt++;
130 | 	}
131 | 
132 | 	exec_multi_threads_on_data(arr_src, N, td_num, exec_e);
133 | 	
134 | 	return 0; 
135 | }
136 | 


--------------------------------------------------------------------------------
/03_reduce/Makefile:
--------------------------------------------------------------------------------
 1 | CC = g++ -std=c++11 
 2 | 
 3 | nullstring := 
 4 | dep_I_incpath = -I./include/hiredis -I./include
 5 | dep_L_libpath = -L./lib
 6 | dep_l_libname = -lhiredis
 7 | #deps_extra = $(dep_I_incpath) $(dep_L_libpath)  $(dep_l_libname)
 8 | 
 9 | deps_extra = $(nullstring)
10 | 
11 | #c_flag = -g -Wno-format -fpermissive 
12 | c_flag = -g -pthread -Wno-format -fpermissive -fopenmp
13 | 
14 | c_files =  \
15 | $(wildcard *.cpp) $(wildcard *.c) $(wildcard *.cc)
16 | h_files = \
17 | $(wildcard *.hpp) $(wildcard *.h)
18 | o_files_mess = \
19 | $(patsubst %.cpp,%.o,${c_files}) $(patsubst %.c,%.o,${c_files}) $(patsubst %.cc,%.o,${c_files})
20 | o_files = \
21 | $(filter %.o, $(o_files_mess))
22 | elf_file=  \
23 | mainapp.exe
24 | 
25 | rm_files = \
26 | *.o *.dep *.elf  *.s *.exe
27 | 
28 | 
29 | all:$(elf_file)
30 | 
31 | $(elf_file):$(o_files)
32 | 	$(CC) $(c_flag) -o $@ $(o_files) $(deps_extra) 
33 | main.o: main.cpp
34 | 	$(CC) $(c_flag) -o $@ -c $< $(deps_extra) 
35 | #	@echo "c_file is:$(c_files)"; echo "h_files:$(h_files)"; echo "o_files:$(o_files)"
36 | 
37 | clean:
38 | 	rm -rf $(rm_files)
39 | 
40 | run:$(elf_file)
41 | 	./$(elf_file)
42 | 
43 | 


--------------------------------------------------------------------------------
/03_reduce/main.cpp:
--------------------------------------------------------------------------------
 1 | #include <iostream>
 2 | #include <omp.h>
 3 | 
 4 | using namespace std; 
 5 | 
 6 | int main()
 7 | {
 8 | 
 9 | #if 0
10 | // TODO : this is incorrect way to reduce !!!
11 | 	int sum = 0;
12 | 	#pragma omp parallel for num_threads(33)
13 | 	for(int i=0; i<100; i++)
14 | 	{
15 | 		sum +=  i; 
16 | 	}
17 | 
18 | 	cout << sum << endl; 
19 | 
20 | #endif 
21 | 
22 | #if 1 
23 | 
24 | 	int sum = 0;
25 | 	#pragma omp parallel for num_threads(32) reduction(+:sum)
26 | 	for(int i=0; i<100; i++)
27 | 	{
28 | 		sum +=  i; 
29 | 	}
30 | 
31 | 	cout << sum << endl; 
32 | 
33 | #endif 
34 | 	
35 | 	return 0; 
36 | }
37 | 
38 | 


--------------------------------------------------------------------------------
/04_get_idx/Makefile:
--------------------------------------------------------------------------------
 1 | CC = g++ -std=c++11 
 2 | 
 3 | nullstring := 
 4 | dep_I_incpath = -I./include/hiredis -I./include
 5 | dep_L_libpath = -L./lib
 6 | dep_l_libname = -lhiredis
 7 | #deps_extra = $(dep_I_incpath) $(dep_L_libpath)  $(dep_l_libname)
 8 | 
 9 | deps_extra = $(nullstring)
10 | 
11 | #c_flag = -g -Wno-format -fpermissive 
12 | c_flag = -g -pthread -Wno-format -fpermissive -fopenmp
13 | 
14 | c_files =  \
15 | $(wildcard *.cpp) $(wildcard *.c) $(wildcard *.cc)
16 | h_files = \
17 | $(wildcard *.hpp) $(wildcard *.h)
18 | o_files_mess = \
19 | $(patsubst %.cpp,%.o,${c_files}) $(patsubst %.c,%.o,${c_files}) $(patsubst %.cc,%.o,${c_files})
20 | o_files = \
21 | $(filter %.o, $(o_files_mess))
22 | elf_file=  \
23 | mainapp.exe
24 | 
25 | rm_files = \
26 | *.o *.dep *.elf  *.s *.exe
27 | 
28 | 
29 | all:$(elf_file)
30 | 
31 | $(elf_file):$(o_files)
32 | 	$(CC) $(c_flag) -o $@ $(o_files) $(deps_extra) 
33 | main.o: main.cpp
34 | 	$(CC) $(c_flag) -o $@ -c $< $(deps_extra) 
35 | #	@echo "c_file is:$(c_files)"; echo "h_files:$(h_files)"; echo "o_files:$(o_files)"
36 | 
37 | clean:
38 | 	rm -rf $(rm_files)
39 | 
40 | run:$(elf_file)
41 | 	./$(elf_file)
42 | 
43 | 


--------------------------------------------------------------------------------
/04_get_idx/main.cpp:
--------------------------------------------------------------------------------
 1 | #include <iostream>
 2 | #include <omp.h>
 3 | #include <cstdio> 
 4 | 
 5 | using namespace std; 
 6 | 
 7 | #define DEFINE_idx auto idx = omp_get_thread_num();
 8 | #define _ROWS (omp_get_num_threads())
 9 | 
10 | 
11 | int main()
12 | {
13 | 
14 | 
15 | 
16 | 	#pragma omp parallel for num_threads(3) 
17 | 
18 | 	for(int i=0; i<10; i++)
19 | 	{
20 | 		DEFINE_idx;
21 | 		printf("- idx is %d, i is %d, total thread num is %d\n", idx, i, _ROWS); 
22 | 	}
23 | 
24 | 	
25 | 	return 0; 
26 | }
27 | 
28 | 


--------------------------------------------------------------------------------
/05_atomic_barrier/Makefile:
--------------------------------------------------------------------------------
 1 | CC = g++ -std=c++11 
 2 | 
 3 | nullstring := 
 4 | dep_I_incpath = -I./include/hiredis -I./include
 5 | dep_L_libpath = -L./lib
 6 | dep_l_libname = -lhiredis
 7 | #deps_extra = $(dep_I_incpath) $(dep_L_libpath)  $(dep_l_libname)
 8 | 
 9 | deps_extra = $(nullstring)
10 | 
11 | #c_flag = -g -Wno-format -fpermissive 
12 | c_flag = -g -pthread -Wno-format -fpermissive -fopenmp
13 | 
14 | c_files =  \
15 | $(wildcard *.cpp) $(wildcard *.c) $(wildcard *.cc)
16 | h_files = \
17 | $(wildcard *.hpp) $(wildcard *.h)
18 | o_files_mess = \
19 | $(patsubst %.cpp,%.o,${c_files}) $(patsubst %.c,%.o,${c_files}) $(patsubst %.cc,%.o,${c_files})
20 | o_files = \
21 | $(filter %.o, $(o_files_mess))
22 | elf_file=  \
23 | mainapp.exe
24 | 
25 | rm_files = \
26 | *.o *.dep *.elf  *.s *.exe
27 | 
28 | 
29 | all:$(elf_file)
30 | 
31 | $(elf_file):$(o_files)
32 | 	$(CC) $(c_flag) -o $@ $(o_files) $(deps_extra) 
33 | main.o: main.cpp
34 | 	$(CC) $(c_flag) -o $@ -c $< $(deps_extra) 
35 | #	@echo "c_file is:$(c_files)"; echo "h_files:$(h_files)"; echo "o_files:$(o_files)"
36 | 
37 | clean:
38 | 	rm -rf $(rm_files)
39 | 
40 | run:$(elf_file)
41 | 	./$(elf_file)
42 | 
43 | 


--------------------------------------------------------------------------------
/05_atomic_barrier/main.cpp:
--------------------------------------------------------------------------------
 1 | #include <iostream>
 2 | #include <omp.h>
 3 | #include <cstdio> 
 4 | 
 5 | using namespace std; 
 6 | 
 7 | #define DEFINE_idx auto idx = omp_get_thread_num();
 8 | #define _ROWS (omp_get_num_threads())
 9 | 
10 | 
11 | int main()
12 | {
13 | 
14 | 
15 | 	int sum = 0; 
16 | #pragma omp parallel  num_threads(3) 
17 | 	{
18 | #pragma omp atomic 
19 | 		sum += 10; 
20 | #pragma omp barrier  // TODO : disable this to see 
21 | 		cout << sum << endl; 
22 | 	}
23 | 
24 | 	return 0; 
25 | }
26 | 
27 | 


--------------------------------------------------------------------------------
/06_mix/Makefile:
--------------------------------------------------------------------------------
 1 | CC = g++ -std=c++11 
 2 | 
 3 | nullstring := 
 4 | dep_I_incpath = -I./include/hiredis -I./include
 5 | dep_L_libpath = -L./lib
 6 | dep_l_libname = -lhiredis
 7 | #deps_extra = $(dep_I_incpath) $(dep_L_libpath)  $(dep_l_libname)
 8 | 
 9 | deps_extra = $(nullstring)
10 | 
11 | #c_flag = -g -Wno-format -fpermissive 
12 | c_flag = -g -pthread -Wno-format -fpermissive -fopenmp
13 | 
14 | c_files =  \
15 | $(wildcard *.cpp) $(wildcard *.c) $(wildcard *.cc)
16 | h_files = \
17 | $(wildcard *.hpp) $(wildcard *.h)
18 | o_files_mess = \
19 | $(patsubst %.cpp,%.o,${c_files}) $(patsubst %.c,%.o,${c_files}) $(patsubst %.cc,%.o,${c_files})
20 | o_files = \
21 | $(filter %.o, $(o_files_mess))
22 | elf_file=  \
23 | mainapp.exe
24 | 
25 | rm_files = \
26 | *.o *.dep *.elf  *.s *.exe
27 | 
28 | 
29 | all:$(elf_file)
30 | 
31 | $(elf_file):$(o_files)
32 | 	$(CC) $(c_flag) -o $@ $(o_files) $(deps_extra) 
33 | main.o: main.cpp
34 | 	$(CC) $(c_flag) -o $@ -c $< $(deps_extra) 
35 | #	@echo "c_file is:$(c_files)"; echo "h_files:$(h_files)"; echo "o_files:$(o_files)"
36 | 
37 | clean:
38 | 	rm -rf $(rm_files)
39 | 
40 | run:$(elf_file)
41 | 	./$(elf_file)
42 | 
43 | 


--------------------------------------------------------------------------------
/06_mix/main.cpp:
--------------------------------------------------------------------------------
 1 | #include <iostream>
 2 | #include <omp.h>
 3 | #include <vector>
 4 | #include <cstdio> 
 5 | #include <cmath>
 6 | #include <algorithm>
 7 | #include <time.h>
 8 | #include <sys/time.h>
 9 | 
10 | 
11 | 
12 | using namespace std; 
13 | 
14 | #define DEFINE_idx auto idx = omp_get_thread_num();
15 | #define _ROWS (omp_get_num_threads())
16 | 
17 | 
18 | int main()
19 | {
20 | 
21 | 	auto diff_in_seconds_jd = [](timeval *end, timeval *start)
22 | 	{
23 | 		double sec;
24 | 		sec=(end->tv_sec - start->tv_sec);
25 | 		sec+=(end->tv_usec - start->tv_usec)/1e6;
26 | 		return sec;
27 | 	};
28 | 
29 | 	struct timeval start, end;
30 | 
31 | 	vector<int> v_i{}; 
32 | 
33 | 	int len = int(1e7); 
34 | 	v_i.resize(len); 
35 | 	vector<int> v_ans {}; 
36 | 	v_ans.resize(len); 
37 | 	
38 | 
39 | 	for(int i=0;i<len;i++)
40 | 	{
41 | 		v_i[i] = i; 	
42 | 	}
43 | 
44 | 	int cnt_ans = 0; 
45 | 
46 | 	v_i[len - 1] = 2; 
47 | 
48 | 	gettimeofday (&start, NULL);  // time start
49 | 	
50 | #pragma omp parallel for reduction(+:cnt_ans) default(shared)  num_threads(10)
51 |         for(int i=0; i<len; i++)
52 | 	{
53 | 		auto &e = v_i[i]; 
54 | 		int t = 0; 
55 | 
56 | 		if ( i < len / 2)
57 | 		{
58 | 			t = pow(e, 2); 
59 | 		}	
60 | 		else 
61 | 		{
62 | 			t = (int)sqrt(e); 
63 | 		}
64 | 		if ( t % 2 == 1)
65 | 		{
66 | 			cnt_ans += 1;
67 | 		}
68 | 	}
69 | 	
70 | 	gettimeofday (&end, NULL); // time end
71 | 	auto time_used = diff_in_seconds_jd(&end, &start); 
72 | 	printf("- time used:\t%f seconds\n", time_used); 
73 | 
74 | 	cout << "- size of v_ans:\t" << cnt_ans << endl; 
75 | 
76 | 
77 | 	for(auto &e : v_ans)
78 | 	{
79 | 		//cout << e << endl; 
80 | 	}
81 | 
82 | 
83 | 
84 | 	return 0; 
85 | }
86 | 
87 | 


--------------------------------------------------------------------------------
/LICENSE:
--------------------------------------------------------------------------------
 1 | MIT License
 2 | 
 3 | Copyright (c) 2019 Jidor
 4 | 
 5 | Permission is hereby granted, free of charge, to any person obtaining a copy
 6 | of this software and associated documentation files (the "Software"), to deal
 7 | in the Software without restriction, including without limitation the rights
 8 | to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
 9 | copies of the Software, and to permit persons to whom the Software is
10 | furnished to do so, subject to the following conditions:
11 | 
12 | The above copyright notice and this permission notice shall be included in all
13 | copies or substantial portions of the Software.
14 | 
15 | THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
16 | IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
17 | FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
18 | AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
19 | LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
20 | OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
21 | SOFTWARE.
22 | 


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/README.md:
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 1 | # openmp_demo
 2 | a demo for openmp , by Jidor
 3 | 
 4 | this project initially created by one of my artical in GitChat. see the link page: 
 5 | 
 6 | [OpenMP at GitChat](https://gitbook.cn/gitchat/activity/5c90f5e6eed4492881242cea)
 7 | 
 8 | 
 9 | all examples can run by command `make run`
10 | 
11 | more ref, please read: `https://www.openmp.org/wp-content/uploads/OpenMP-API-Specification-5.0.pdf`
12 | ## 00_dep
13 | demo assertion of environment and dependencies.
14 | 
15 | ## 01_parallel_cout
16 | demo parallel print out 
17 | 
18 | ## 02_parallel_no_omp
19 | demo if not use openmp, what will the code looks like
20 | 
21 | ## 03_reduce
22 | demo a reduce 
23 | 
24 | ## 04_get_idx
25 | demo ways to get thread idx
26 | 
27 | ## 05_atomic_barrier
28 | demo atomic and barrier 
29 | 
30 | ## 06_mix
31 | demo an advanced example
32 | 
33 | 
34 | ## donate && support
35 | 最后，如果有帮助，谢谢支持和推广哦~
36 | 
37 | 
38 | ![alipay_QR](./.img/alipay_jd_t.png)
39 | 


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