bug: Memory usage reporting incorrectly

It says 100% but actually only 20GB/64GB is used. Rest is used for disposable cache, which should not be considered in this calculation.

Output of free command at the server;

# free
             total       used       free     shared    buffers     cached
Mem:      66025196   65682236     342960       1068     271752   44275056
-/+ buffers/cache:   21135428   44889768
Swap:            0          0          0