Virtual Memory Management

Changes to the base system formerly available only with the UnixWare 7 Release 7.1.1 Virtual Memory Management (VMM) Feature Supplement are integrated into Open UNIX 8.

Several improvements in memory management, performance, and related tools are provided:

• Up to 16GB of general purpose memory can now be used, because it can be divided into memory used by a process to cache file data, and memory used by a process otherwise. A new tunable, FILE_PAGES_MAX, controls the amount of memory that can be reserved for caching file data. This tunable is discussed in ``New and changed VMM tunables''.

• Performance is improved by introducing the ``bin hopping'' algorithm in allocation of physical pages, thereby reducing cache replacement traffic. The operating system now also exhibits better concurrency on large multi-processor machines through the ``splitting'' of several global locks (including VM_PAGEFREELOCK, an_refl_lck, and the anon VN_PGLOCK).

• The system is made safe from minor streams leaks, through the introduction of a delayed abort feature for sendv. Previously, a minor leak could both degrade the performance of a large memory system over a period of months, and hang the system in minutes.

• Several tools, including sar(1M) memsize(1M), and rtpm(1M), have been enhanced with respect to reporting memory usage and disk statistics.