1. A method of adjusting memory allocation of a partition in a partitioned data processing system, the method comprising: collecting, by a processor, over a first measurement interval, statistics on a paging rate at which pages are transferred between an uncompressed memory space and a compressed memory space of the partition's main memory, wherein uncompressed pages are stored in the uncompressed memory space and compressed pages are stored in the compressed memory space; subsequent to the collecting over the first measurement interval, adjusting size of the uncompressed memory space of the partition's main memory; and subsequent to the adjusting, collecting, over a second measurement interval, statistics on the paging rate at which pages are transferred between the uncompressed memory space and the compressed memory space of the partition's main memory, and referencing the resulting measurement interval statistics in determining an acceptable main memory allocation for the partition.