Described embodiments provide a memory manager for a network processor having a plurality of processing modules and a shared memory. The memory manager allocates blocks of the shared memory to requesting ones of the plurality of processing modules. A free block list tracks availability of memory blocks of the shared memory. A reference counter maintains, for each allocated memory block, a reference count indicating a number of access requests to the memory block by ones of the plurality of processing modules. The reference count is located with data at the allocated memory block. For subsequent access requests to a given memory block concurrent with processing of a prior access request to the memory block, a memory access accumulator (i) accumulates an incremental value corresponding to the subsequent access requests, (ii) updates the reference count associated with the memory block, and (iii) updates the memory block with the accumulated result.