performance measurements
Each table row shows performance measurements for this C gcc program with a particular command-line input value N.
| N | CPU secs | Elapsed secs | Memory KB | Code B | ≈ CPU Load |
|---|---|---|---|---|---|
| 1,000 | 0.10 | 0.10 | ? | 799 | 0% 0% 0% 100% |
| 4,000 | 1.48 | 1.49 | 2,008 | 799 | 0% 0% 1% 100% |
| 16,000 | 23.54 | 23.55 | 29,728 | 799 | 0% 0% 0% 100% |
Read the ↓ make, command line, and program output logs to see how this program was run.
Read mandelbrot benchmark to see what this program should do.
notes
gcc (Ubuntu/Linaro 4.7.3-1ubuntu1) 4.7.3
mandelbrot C gcc #4 program source code
/* The Computer Language Benchmarks Game * http://benchmarksgame.alioth.debian.org/ contributed by Paolo Bonzini further optimized by Jason Garrett-Glaser pthreads added by Eckehard Berns further optimized by Ryan Henszey modified by Samy Al Bahra (use GCC atomic builtins) modified by Kenneth Jonsson */ #include <stdint.h> #include <stdio.h> #include <stdlib.h> typedef double v2df __attribute__ ((vector_size(16))); /* vector of two doubles */ typedef int v4si __attribute__ ((vector_size(16))); /* vector of four ints */ const v2df zero = { 0.0, 0.0 }; const v2df four = { 4.0, 4.0 }; /* * Constant throughout the program, value depends on N */ int bytes_per_row; double inverse_w; double inverse_h; /* * Program argument: height and width of the image */ int N; /* * Lookup table for initial real-axis value */ v2df *Crvs; /* * Mandelbrot bitmap */ uint8_t *bitmap; static void calc_row(int y) { uint8_t *row_bitmap = bitmap + (bytes_per_row * y); int x; const v2df Civ_init = { y*inverse_h-1.0, y*inverse_h-1.0 }; for (x=0; x<N; x+=2) { v2df Crv = Crvs[x >> 1]; v2df Civ = Civ_init; v2df Zrv = zero; v2df Ziv = zero; v2df Trv = zero; v2df Tiv = zero; int i = 50; int two_pixels; v2df is_still_bounded; do { Ziv = (Zrv*Ziv) + (Zrv*Ziv) + Civ; Zrv = Trv - Tiv + Crv; Trv = Zrv * Zrv; Tiv = Ziv * Ziv; /* * All bits will be set to 1 if 'Trv + Tiv' is less than 4 * and all bits will be set to 0 otherwise. Two elements * are calculated in parallel here. */ is_still_bounded = __builtin_ia32_cmplepd(Trv + Tiv, four); /* * Move the sign-bit of the low element to bit 0, move the * sign-bit of the high element to bit 1. The result is * that the pixel will be set if the calculation was * bounded. */ two_pixels = __builtin_ia32_movmskpd(is_still_bounded); } while (--i > 0 && two_pixels); /* * The pixel bits must be in the most and second most * significant position */ two_pixels <<= 6; /* * Add the two pixels to the bitmap, all bits are * initially zero since the area was allocated with * calloc() */ row_bitmap[x >> 3] |= (uint8_t) (two_pixels >> (x & 7)); } } int main (int argc, char **argv) { int i; N = atoi(argv[1]); bytes_per_row = (N + 7) >> 3; inverse_w = 2.0 / (bytes_per_row << 3); inverse_h = 2.0 / N; /* * Crvs must be 16-bytes aligned on some CPU:s. */ if (posix_memalign((void**)&Crvs, sizeof(v2df), sizeof(v2df) * N / 2)) return EXIT_FAILURE; #pragma omp parallel for for (i = 0; i < N; i+=2) { v2df Crv = { (i+1.0)*inverse_w-1.5, (i)*inverse_w-1.5 }; Crvs[i >> 1] = Crv; } bitmap = calloc(bytes_per_row, N); if (bitmap == NULL) return EXIT_FAILURE; #pragma omp parallel for schedule(static,1) for (i = 0; i < N; i++) calc_row(i); printf("P4\n%d %d\n", N, N); fwrite(bitmap, bytes_per_row, N, stdout); free(bitmap); free(Crvs); return EXIT_SUCCESS; }
make, command-line, and program output logs
Sat, 27 Apr 2013 23:20:09 GMT MAKE: /usr/bin/gcc -pipe -Wall -O3 -fomit-frame-pointer -march=native -mfpmath=sse -msse2 -fopenmp mandelbrot.gcc-4.c -o mandelbrot.gcc-4.gcc_run rm mandelbrot.gcc-4.c 1.95s to complete and log all make actions COMMAND LINE: ./mandelbrot.gcc-4.gcc_run 16000 (BINARY) PROGRAM OUTPUT NOT SHOWN