fork download
copy 
  1. #include <iostream>
  2. #include <vector>
  3. #include <chrono>
  4. using namespace std;
  5.  
  6. size_t creation1_ns = 0;
  7. size_t creation2_ns = 0;
  8.  
  9. size_t iteration1_ns = 0;
  10. size_t iteration2_ns = 0;
  11.  
  12. double test1(size_t w, size_t h){
  13. 	auto start = chrono::steady_clock::now();
  14. 	vector<vector<double>> data;
  15. 	data.reserve(h);
  16. 	for(size_t row = 0; row < h; ++row){
  17. 		data.emplace_back(vector<double>(w));
  18. 	}
  19. 	creation1_ns += chrono::duration_cast<chrono::nanoseconds>(chrono::steady_clock::now() - start).count();
  20.  
  21. 	start = chrono::steady_clock::now();
  22. 	for(size_t row = 0; row < h; ++row){
  23. 		for(size_t col = 0; col < w; ++col){
  24. 			data[row][col] += rand(); // Write something
  25. 		}	
  26. 	}
  27.  
  28. 	double sum = 0.0;
  29. 	for(size_t row = 0; row < h; ++row){
  30. 		for(size_t col = 0; col < w; ++col){
  31. 			sum += data[row][col]; // Read something
  32. 		}	
  33. 	}
  34. 	iteration1_ns += chrono::duration_cast<chrono::nanoseconds>(chrono::steady_clock::now() - start).count();
  35.  
  36. 	return sum;
  37. }
  38.  
  39.  
  40. double test2(size_t w, size_t h){
  41. 	auto start = chrono::steady_clock::now();
  42. 	vector<double> data(w*h);
  43. 	creation2_ns += chrono::duration_cast<chrono::nanoseconds>(chrono::steady_clock::now() - start).count();
  44.  
  45. 	start = chrono::steady_clock::now();
  46. 	for(size_t row = 0; row < h; ++row){
  47. 		size_t offs = row*w;
  48. 		for(size_t col = 0; col < w; ++col){
  49. 			data[offs + col] += rand(); // Write something
  50. 		}	
  51. 	}
  52.  
  53. 	double sum = 0.0;
  54. 	for(size_t row = 0; row < h; ++row){
  55. 		size_t offs = row*w;
  56. 		for(size_t col = 0; col < w; ++col){
  57. 			sum += data[offs + col]; // Read something
  58. 		}	
  59. 	}
  60. 	iteration2_ns += chrono::duration_cast<chrono::nanoseconds>(chrono::steady_clock::now() - start).count();
  61.  
  62. 	return sum;
  63. }
  64.  
  65. int main() {
  66.     srand(2);
  67. 	const auto thoroughness = 50000.0;
  68. 	auto s = 0;
  69.  
  70. 	for(int h = 16; h < 10000; h *= 8){
  71. 		for(int w = 16; w < 10000; w *= 8){
  72. 			creation1_ns = 0;
  73. 			creation2_ns = 0;
  74. 			iteration1_ns = 0;
  75. 			iteration2_ns = 0;
  76.  
  77.             auto trials = thoroughness/(w*h);
  78.  
  79. 			for(int r = 0; r < trials; ++r){
  80. 				s+= test1(w, h);
  81. 				s+= test2(w, h);
  82. 			}
  83.  
  84. 			cout<<w<<"x"<<h
  85. 				<<" alloc speed up: "<< (double(creation1_ns) / creation2_ns)<<"x"
  86. 				<<" iter speed up: "<< (double(iteration1_ns) / iteration2_ns)<<"x" <<endl;	
  87. 		}
  88. 	}
  89.  
  90.  
  91. 	cout<<"print sum to avoid the code from being removed: "<<s<<endl;
  92. 	return 0;
  93. }
  94.  
Success #stdin #stdout 2.72s 3472KB
comments (?)
stdin
copy 
Standard input is empty
stdout
copy 
16x16 alloc speed up: 1.97028x iter speed up: 1.01526x
128x16 alloc speed up: 1.62749x iter speed up: 1.08437x
1024x16 alloc speed up: 1.96126x iter speed up: 0.818857x
8192x16 alloc speed up: 1.08617x iter speed up: 1.07597x
16x128 alloc speed up: 2.60728x iter speed up: 1.05362x
128x128 alloc speed up: 1.9301x iter speed up: 1.05701x
1024x128 alloc speed up: 1.10907x iter speed up: 1.06326x
8192x128 alloc speed up: 1.07762x iter speed up: 1.04457x
16x1024 alloc speed up: 5.71674x iter speed up: 1.0753x
128x1024 alloc speed up: 1.1498x iter speed up: 1.02847x
1024x1024 alloc speed up: 1.03182x iter speed up: 1.04656x
8192x1024 alloc speed up: 1.02505x iter speed up: 1.00829x
16x8192 alloc speed up: 2.1236x iter speed up: 1.07109x
128x8192 alloc speed up: 1.16434x iter speed up: 1.04066x
1024x8192 alloc speed up: 1.16075x iter speed up: 1.03849x
8192x8192 alloc speed up: 1.0298x iter speed up: 1.04191x
print sum to avoid the code from being removed: -2147483648
https://ideone.com/GJvQqT
language:
C++14 (gcc 8.3)
created:
7 years ago
visibility:
public

Share or Embed source code

Discover > Sphere Engine API

The brand new service which powers Ideone!

Discover > IDE Widget

Widget for compiling and running the source code in a web browser!