Xeon         AMD64
single process, empty loop     420,000/s    360,000/s
two processes, empty loop      330,000/s    220,000/s
single process, gettimeofday   230,000/s    110,000/s
two processes, gettimeofday    180,000/s    87,000/s

##</code><code>##

#!perl -slw
use strict;
use threads;
use POSIX qw( WNOHANG );
use Time::HiRes qw(gettimeofday);
use Inline C => <<'END_OF_CODE';
#include <sched.h>

void yield_me() {
    sched_yield();
  }
END_OF_CODE


my (@time,$a);
sub thread{
  while (1) {
#    gettimeofday();
    yield_me()
  }
}
my @forks = map{ if (my $pid=fork){waitpid(-1,WNOHANG)}elsif($pid==0){thread()}else{die "Cannot fork"} } 1 .. 10;

<STDIN>;

##</code><code>##

                               Xeon        AMD64
single process, empty loop     865,000/s   550,000/s
two processes, empty loop      845,000     525,000/s
single process, gettimeofday   345,000     130,000/s
two processes, gettimeofday    340,000     125,000/s