Mysqld memory load

I’m using version: 5.5.28-29.1 Percona Server (GPL), Release 29.1
3 days ago mysql starts to eat more memory, than usually.
And I cant find why. Load is the same for a long period of time. Restart doesnt help.
I`ve attached munin graph. Can anyone help to find problem?

You mean it is using less memory. Maybe you restarted it, and old pages do not fill the buffer pool as they have not been read yet.

I mean that Percona was using less memory than now.