These measurements were done on a PA-RISC 720 machine with only 16Mbytes of memory (the other measurements used machines with 32Mbytes of memory). This means that swapping starts at lighter loads, so one sees the effects of the VM enhancements more clearly. The curves labelled "MK6 + VM" and "MK6 w/o VM" are respectively the MK6-PA system with and without the VM enhancements. The third curve (labelled "HP-UX") represents the results for HP-UX 9.05 on the same machine. So without the VM enhancements MK6-PA performs less well than HP-UX above about 120 users, whereas with the VM enhancements MK6-PA is faster than HP-UX for heavy loads.