hi,
Is it desirable/necessary?
It depends of what you want to do and if you know what to do with it !

First method : with epel repo
yum --enablerepo=epel info php-eaccelerator
yum --enablerepo=epel install php-eaccelerator
php -v
Second method : with sources from
http://eaccelerator.net or
https://github.com/eaccelerator/eacceleratoryou download, you unzip or untar and of course you read the README file !!!!!
phpize
./configure --enable-eaccelerator=shared --with-php-config=/usr/bin/php-config && make && make install
If you know what to do then you can tweak the "/etc/php.d/eaccelerator.ini" and "/proc/sys/kernel/shmmax"
else don't even try and go to read a good cook book on PHP code caching or on compiling PHP code !

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