I installed eAccelerator this is my eaccelerator.ini
extension="eaccelerator.so"
eaccelerator.shm_size="32"
eaccelerator.cache_dir="/var/cache/eaccelerator"
eaccelerator.enable="1"
eaccelerator.optimizer="1"
eaccelerator.check_mtime="1"
eaccelerator.debug="0"
eaccelerator.filter=""
eaccelerator.shm_max="0"
eaccelerator.shm_ttl="0"
eaccelerator.shm_prune_period="0"
eaccelerator.shm_only="0"
eaccelerator.compress="1"
eaccelerator.compress_level="9"
but after installed eAccelerator I got 500 errors from server. Then I changed /etc/sysctl.conf (set kernel.shmmax = 536870912 and use command sysctl -p) and changed eaccelerator.ini (eaccelerator.shm_size="32") And I again got 500 errors from server.