title: PHP APC installed but not enabled
body: <p>on an amazon linux ami I've succesfully (I think) installed apc (with yum or pecl. tried both) but I'm not able to enable it (sorry for the pun).</p>
  
  <p>php -i says:</p>
  
  <pre><code>apc
  
  APC Support =&gt; disabled
  Version =&gt; 3.1.15-dev
  APC Debugging =&gt; Disabled
  MMAP Support =&gt; Enabled
  MMAP File Mask =&gt;
  Locking type =&gt; pthread mutex Locks
  Serialization Support =&gt; broken
  Revision =&gt; $Revision: 329725 $
  Build Date =&gt; May 28 2013 18:03:40
  
  Directive =&gt; Local Value =&gt; Master Value
  apc.cache_by_default =&gt; On =&gt; On
  </code></pre>
  
  <p>(and so on...)</p>
  
  <p>extension=apc.so and apc.enabled=1 are in /etc/php.d/apc.ini (and php -i confirm that /etc/php.d/apc.ini is parsed). 
  I tried also to put them in /etc/php.ini to no avail. (And of course I dutifully restarted httpd every time). 
  Now I really don't know what to do...</p>