Allowed memory size exhausted

I am getting following error in “Visitor in Real Time” window

Fatal error: Allowed memory size of 134217728 bytes exhausted (tried to allocate 4 bytes) in /var/www/html/owa/piwik/libs/Zend/Db/Statement/Pdo.php on line 290

I have a virtual machine with 1 vCPU and 1 GB memory.

Change in /etc/php.ini fixed my issue. But what is the recommanded value?

memory_limit = 128M


memory_limit = 256M

fixed my issue