Observed the same heap utilization in the JConsole tool and SMA for heap. But when comparing to total utilization of the RAM from server is getting deviation.
RES in TOP command is total RAM utilizing by the application which means Heap+NonHeap. In our case the total RAM allocated for application is 7Gb (Heap 6GB + Non Heap 1GB). Observed 2GB free Heap in SMA. That means 4GB Heap was utilized , if we assume the non heap was completely occupied then the total utilized should be 6GB (Heap 4GB+NonHeap 1GB) only.
But the RAM utilization for application is 7 GB in server level.
RAM utilization seen through TOP or free command will always be more than heap because your System has other background processes running other than pega . These OS processes would also consume some RAM and some level of deviation would be there.
We have observed the values related to the PRPC process only. TOP is displaying the RAM utilization of all the processes individually. We referred to the PRPC process so it will not include the OS utilization. Due to the difference in calculations there could be some deviation but not this much.