High iowait and/or load average when APC enabled in PHP Selector

If you are experiencing high iowait or high IO usage by single LVE or load average jumps after enabling APC, the most probable reason is due to the following directive in /opt/alt/php5*/etc/php.d.all/apc.ini:

apc.mmap_file_mask = /tmp/apc.shm.XXXXXX

There are articles on the Internet related to the same subject, for example, http://serverfault.com/questions/361032/high-disk-i-o-when-cache-is-used . We decided to change it to /dev/zero by default,  the same will be applied to all new installations. For existing installs you need to edit each /opt/alt/php5*/etc/php.d.all/apc.ini then execute:

cagefsctl --rebuild-alt-php-ini