In an approach for improving data access performance in memory, a processor monitors each data access to a data element in the memory from an application, wherein the application has a plurality of functions. A processor records, during runtime, each data access into a monitoring element table, wherein the record for each data access includes an identity, a start address, an end address, and a memory page number. A processor clusters recorded data accesses for each function based on a distance between data elements accessed in sequence. A processor allocates, based on the data element clustering result, the data elements in a same cluster into a same memory unit in the memory.