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VADVISE(2)                    System Calls Manual                   VADVISE(2)



NAME
       vadvise - give advice to paging system

SYNOPSIS
       #include <&lt;sys/vadvise.h>&gt;
       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 <&lt;sys/vadvise.h>.  Currently, two calls to vadvise() are imple-
       mented.

              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.



                                21 January 1990                     VADVISE(2)