A memory allocator in a computer system comprising a plurality of CPU cores (5101-5104) and a first (530) and a second (5120) memory unit having different data access times and wherein each one of the first and the second memory units is divided into memory portions wherein each memory portion (SLICE 0-3) in the second memory unit is associated with at least one memory portion (A-G) in the first memory unit, and wherein each memory portion in the second memory unit is associated with a CPU core. If at least a predetermined number of memory portions in the first memory unit being part of the available requested memory is associated with the memory portion in the second memory unit that is associated with the CPU core on which the requesting application is running, the requested available memory is allocated to the requesting application.