Performance-Optimized Page Sizing (POPS)

	NOTE: Performance-Optimized Page Sizing is often referred to as Variable Page Sizing.

Performance-Optimized Page Sizing (POPS) now provides the potential for improved performance to ALL processes on processors that support POPS (for example, PCX-U processors). Previous releases provided POPS only to processes that locked their image into physical memory with plock(2).

The POPS feature enables administrators to specify how large a page size an application can use. This is most useful on heavily loaded systems experiencing table lookaside buffer thrashing. It is available only on PA-8xx-based systems.

Existing options to chatr(1) allow the user to specify the optimum page size for a given executable. See the chatr(1) man page for more details. In the absence of a chatr "hint", heuristics will transparently determine the optimum page size. These heuristics are configurable via new kernel tunables.

Additional information is available in the "HP-UX 11.0 Performance Optimized Page Sizing" whitepaper at the Electronic Support Center (formerly known as HP Supportline).

Performance

The heuristics used to transparently determine optimum page size, in conjunction with the default values for the new kernel tunables, may not be effective for all executables and environments. Performance may be degraded.

If the heuristics and default tunable values do not provide satisfactory performance, users may want to modify the tunables and/or use the chatr functionality to hand-tune the optimum page size. New tools that analyze a process's run-time behavior will assist users in selecting the correct page size. See the chatr(1) man page.

Performance-Optimized Pages functionality will only be visible to machines that support this feature (for example, PCX-U processors).