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 <vadvise.h>.  Currently, two calls t vadvise are implemented. 

The call

vadvise(VA_ANOM);

advises that the paging behavior is not likely to be well handled by the system’s default algorithm, since reference information is collected over macroscopic intervals (e.g. 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. 

The call

vadvise(VA_NORM);

restores default paging replacement behavior after a call to

vadvise(VA_ANOM);

BUGS

Will go away soon, being replaced by a per-page madvise facility. 

Sun Release 3.2  —  Last change: 20 August 1985