on MX10k with FPC LC2101 or LC480 , FPC heap memory utilization  will increase by (i.e 11%-12%) after junos upgrade from any release prior 22.1R1 to any release post 22.1R1 (i.e from 21.2R3-S5 to 22.4R3-S2) due to adding a new feature to support soft reset of PFE (Packet Forwarding Engine ). PFE soft reset feature needs to shadow every PFE RO_BULK_DMEM in FPC ukernel heap. this leads to noticeable increase of heap memory and this increase depends on the size of the RO_BULK_DMEM .

Note: RO_BULK_DMEM pool is used by some JNH partitions like "Next Hop" and "Service NH" . Service NH partition is used to store Inline Jflow data. so this partition will be increased with enabling inline jflow and hence increase in the heap memory of FPC

FPC heap memory utilization  for LC2101 will increase after junos upgrade to any version after 22.1

Before junos upgrade:

user @router> show chassis fpc

Temp CPU Utilization (%) CPU Utilization (%) Memory Utilization (%)

Slot State (C) Total Interrupt 1min 5min 15min DRAM (MB) Heap Buffer

0 Online 48 46 2 43 47 47 3168 63 30  <-- LC2101 heap memory utilization before the upgrade

1 Online 47 43 0 42 43 42 3168 62 30  <-- LC2101 heap memory utilization before the upgrade

After junos upgrade:
 

user @router> show chassis fpc

Temp CPU Utilization (%) CPU Utilization (%) Memory Utilization (%)

Slot State (C) Total Interrupt 1min 5min 15min DRAM (MB) Heap Buffer

0 Online 54 29 1 32 34 34 3168 74 30 <-- LC2101 heap memory utilization after the upgrade

1 Online 52 29 0 30 30 30 3168 74 30 <-- LC2101 heap memory utilization after the upgrade

this is an expected behavior to support soft reset of PFE feature that needs to copy the content of RO_BULK_DMEM memory to ukernel heap memory , and typically that happens across all PFEs at this FPC. So the more PFEs an FPC has, the more pronounced the heap usage increase will be in post RLI35196