#include <stdio.h>
#include <stdlib.h>
#include <unistd.h>
#define __USE_GNU
#include <sched.h>
#include <errno.h>

static unsigned int getcpu()
{
  unsigned int i, cpuid;
  FILE *fp;

  fp=fopen( "/proc/self/stat", "r" );
  if( fp==NULL ) {
    perror( "/proc/self/stat" );
    exit( -1 );
  }
  fscanf( fp, "%*d %*s %*s" );
  for( i=3; i<39; i++ ) // Das 39. Feld enthaelt die CPU-Id.
    fscanf( fp, "%d", &cpuid );
  return cpuid;
}

static unsigned int getaffinity( cpu_set_t *mask )
{
  CPU_ZERO( mask );
  if( sched_getaffinity( getpid(), sizeof(*mask), mask) ) {
    perror("sched_setaffinity");
    exit( -2 );
  }
  return mask->__bits[0]; // XXX - quick hack
}

int main( int argc, char **argv )
{
  cpu_set_t mask;
  int cpuid;

  cpuid = getcpu();
  printf("Aktive CPU: %d\n", cpuid );
  printf("Affinity-Maske: 0x%x\n", getaffinity( &mask ) );
  CPU_CLR( cpuid, &mask ); // Aktuelle CPU ausschliessen.
  printf("Setzen der Affinität auf: 0x%lx\n", mask.__bits[0] );
  if( sched_setaffinity( getpid(), sizeof(mask), &mask ) ) {
    perror("sched_setaffinity"); // UP-System???
  }
  printf("Affinity-Maske: 0x%x\n", getaffinity( &mask ) );
  printf("Aktive CPU %d\n", getcpu() );

  return 0;
}