Clear memory caches on Linux

To free pagecache:

sync; echo 1 > /proc/sys/vm/drop_caches

To free dentries and inodes:

sync; echo 2 > /proc/sys/vm/drop_caches

To free pagecache, dentries and inodes:

sync; echo 3 > /proc/sys/vm/drop_caches

sync should be run because this is a non-destructive operation, and dirty objects are not freeable. So you run sync in order to make sure all cached objects are freed.

Install and set php extention Memcached

yum install gcc gcc-c++


Install the dependency libevent

cd /usr/local/src
curl -O http://monkey.org/~provos/libevent-1.4.14b-stable.tar.gz
tar xzvf libevent-1.4.14b-stable.tar.gz
cd libevent-1.4.14b-stable
./configure --prefix=/usr/local
make && make install

Next, install memcached:

cd /usr/local/src
curl -O http://memcached.googlecode.com/files/memcached-1.4.5.tar.gz
tar xzvf memcached-1.4.5.tar.gz
cd memcached-1.4.5
LDFLAGS='-Wl,--rpath /usr/local/lib' ./configure --prefix=/usr/local
make && make install

Lets install the new PECL memcached extension in your web server. This new extension depends on libmemcached. You can grab the latest distribution of libmemcached from https://launchpad.net/libmemcached and compile it in your own machine. Make sure you have the dependencies met.

cd /usr/local/src
wget http://launchpad.net/libmemcached/1.0/0.44/+download/libmemcached-0.44.tar.gz
tar -zxvf libmemcached-0.44.tar.gz
cd libmemcached-0.44
./configure
make && make install

Considering everything went fine, lets install the PECL memcached extension

pecl install memcached

Build process completed successfully
Installing '/usr/lib64/php/modules/memcached.so'
install ok: channel://pecl.php.net/memcached-1.0.2
configuration option "php_ini" is not set to php.ini location
You should add "extension=memcached.so" to php.ini