VADVISE(2)

NAME
vadvise - give advice to paging system

SYNOPSIS
#include <sys/vadvise.h>

vadvise(param)
int param;

DESCRIPTION
vadvise() is used to inform the system that process paging behavior merits special consideration. Parameters to vadvise() are defined in the file <sys/vadvise.h>. Currently, two calls to vadvise() are implemented.

    vadvise(VA_ANOM);

advises that the paging behavior is not likely to be well handled by the system's default algorithm, since reference information that is collected over macroscopic intervals (for instance, 10-20 seconds) will not serve to indicate future page references. The system in this case will choose to replace pages with little emphasis placed on recent usage, and more emphasis on referenceless circular behavior. It is essential that processes which have very random paging behavior (such as LISP during garbage collection of very large address spaces) call vadvise, as otherwise the system has great difficulty dealing with their page-consumptive demands.

    vadvise(VA_NORM);

restores default paging replacement behavior after a call to

    vadvise(VA_ANOM);

BUGS
The current implementation of vadvise() will go away soon, being replaced by a per-page vadvise() facility.