source code
/*
The Computer Language Benchmarks Game
https://salsa.debian.org/benchmarksgame-team/benchmarksgame/
contributed by Paolo Bonzini
further optimized by Jason Garrett-Glaser
OpenMP by The Anh Tran
10-11-2010, modified by The Anh Tran:
_ copy bit shift idea from C entry
C version by Des Nerger
*/
#include <assert.h>
#include <stdio.h>
#include <stdlib.h>
#include <sched.h>
#include <memory.h>
#include <omp.h>
#include <sys/types.h>
#define L2_CACHE_LINE 64
#define ALIGN __attribute__ ((aligned(L2_CACHE_LINE)))
typedef unsigned char byte;
typedef double v2d __attribute__ ((vector_size(16)));
typedef int32_t v4i __attribute__ ((vector_size(16)));
const v2d v10 = { 1.0, 1.0 };
const v2d v15 = { 1.5, 1.5 };
const v2d v40 = { 4.0, 4.0 };
v2d inv_2n; // {2.0/N, 2.0/N}
int
GetThreadCount()
{
cpu_set_t cs;
CPU_ZERO(&cs);
sched_getaffinity(0, sizeof(cs), &cs);
int count = 0;
for (int i = 0; i < CPU_SETSIZE; ++i)
count += CPU_ISSET(i, &cs);
return count;
}
void
mandelbrot(int N, byte* data)
{
ALIGN int row_processed = 0;
#pragma omp parallel default(shared) num_threads(GetThreadCount())
{
int y = 0;
while ((y = __sync_fetch_and_add(&row_processed, 1)) < N)
{
byte* row_output = data + y * (N >> 3);
v2d Civ = {y, y};
Civ = Civ * inv_2n - v10;
for (int x = 0; x < N; x += 2)
{
v2d Crv = {x+1, x};
Crv = Crv * inv_2n - v15;
v2d Zrv = Crv;
v2d Ziv = Civ;
v2d Trv = Crv * Crv;
v2d Tiv = Civ * Civ;
int result = 3; // assume that 2 elements belong to MB set
int i = 1;
while ( result && (i++ < 50) )
{
v2d ZZ = Zrv * Ziv;
Zrv = Trv - Tiv + Crv;
Ziv = ZZ + ZZ + Civ;
Trv = Zrv * Zrv;
Tiv = Ziv * Ziv;
// trv + tiv <= 4.0
v2d delta = (v2d)__builtin_ia32_cmplepd( (Trv + Tiv), v40 );
result = __builtin_ia32_movmskpd(delta);
}
{
int bit_shift = 6 - (x & 7);
row_output[x >> 3] |= (byte)(result << bit_shift);
}
}
}
}
}
int
main (int argc, char **argv)
{
const int N = (argc == 2) ? (int)strtol(argv[1], NULL, 10) : 200;
assert((N % 8) == 0);
printf("P4\n%d %d\n", N, N);
{
double* p_iv = (double*)(&inv_2n);
p_iv[0] = p_iv[1] = 2.0 / N;
}
const int bytes_count = (N >> 3) * N;
byte* data = 0;
assert( posix_memalign((void**)(&data), L2_CACHE_LINE, bytes_count)
== 0);
memset(data, 0, bytes_count);
mandelbrot(N, data);
fwrite( data, bytes_count, 1, stdout);
fflush(stdout);
free(data);
return 0;
}
notes, command-line, and program output
NOTES:
64-bit Ubuntu quad core
13.2.0-23ubuntu4
Mon, 03 Jun 2024 22:27:07 GMT
MAKE:
/usr/bin/gcc -pipe -Wall -O3 -fomit-frame-pointer -march=ivybridge -D_GNU_SOURCE -fopenmp mandelbrot.gcc-7.c -o mandelbrot.gcc-7.gcc_run
rm mandelbrot.gcc-7.c
2.69s to complete and log all make actions
COMMAND LINE:
./mandelbrot.gcc-7.gcc_run 16000
(BINARY) PROGRAM OUTPUT NOT SHOWN