Spread out your fastcgi processes among the hyperthreads and cores of your CPU

assignhyperthreads.php

<?php

// This script will spread out your php-cgi fastcgi processes
// evenly over the hyperthreads of your server.

// If your php-cgi process is not /usr/local/bin/php-cgi, 
// tweak accordingly.
//
// [email protected], @boutell, punkave.com

$hyperthreadsTotal = count(preg_grep('/^processor/', file('/proc/cpuinfo')));

echo("Total hyperthreads: $hyperthreadsTotal\n");

$pids = glob("/proc/*");

$hyperthread = 0;

foreach ($pids as $pid)
{
  $pid = basename($pid);
  if (preg_match('/^\d+$/', $pid))
  {
    $cmd = file_get_contents("/proc/$pid/cmdline");
    $elements = explode("\x00", $cmd);
    if (count($elements))
    {
      if ($elements[0] === '/usr/local/bin/php-cgi')
      {
        system("taskset -p -c $hyperthread $pid");
        $total++;
        $hyperthread++;
        $hyperthread %= $hyperthreadsTotal;
      }
    }
  }
}

echo("Total fastcgi processes assigned to hyperthreads: $total\n\n");

echo("*** YOU WILL NOT SEE A DIFFERENCE IN checkhyperthreads.php\n");
echo("*** until these processes ACTUALLY RESPOND TO REQUESTS.\n");