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Annotation of 43BSDReno/old/man/vadvise.2v, revision 1.1.1.1

1.1       root        1: .\" Copyright (c) 1980 Regents of the University of California.
                      2: .\" All rights reserved.  The Berkeley software License Agreement
                      3: .\" specifies the terms and conditions for redistribution.
                      4: .\"
                      5: .\"    @(#)vadvise.2v  4.1 (Berkeley) 5/9/85
                      6: .\"
                      7: .TH VADVISE 2V
                      8: .UC 4
                      9: .SH NAME
                     10: vadvise \- give advice to paging system
                     11: .SH SYNOPSIS
                     12: .B vadvise(param)
                     13: .SH DESCRIPTION
                     14: .I Vadvise
                     15: is used to inform the system that process paging behavior merits special
                     16: consideration.  Parameters to
                     17: .I vadvise
                     18: are defined in the file
                     19: .B <vadvise.h> .
                     20: Currently, two calls to
                     21: .I vadvise
                     22: are implemented:
                     23: .PP
                     24: The call
                     25: .IP
                     26: .B "vadvise(VA_ANOM);"
                     27: .LP
                     28: advises that the paging behavior is not likely to
                     29: be well handled by the system's default algorithm, since reference information
                     30: collected over macroscopic intervals (e.g. 10-20 seconds)
                     31: will not serve to indicate future page references.  The system in this case
                     32: will choose to replace pages with little emphasis placed on recent usage,
                     33: and more emphasis on referenceless circular behavior.  It is \fIessential\fR
                     34: that processes which have very random paging behavior (such as
                     35: LISP during garbage collection of very large address spaces) call
                     36: .I vadvise,
                     37: as otherwise the system has great difficulty dealing with their
                     38: page-consumptive demands.
                     39: .PP
                     40: The call
                     41: .IP
                     42: .B "vadvise(VA_NORM);"
                     43: .LP
                     44: restores default paging replacement behavior after a call to
                     45: .IP
                     46: .B "vadvise(VA_ANOM);"
                     47: .SH BUGS
                     48: This call is peculiar to this version of UNIX.
                     49: The options and specifications of this system call and even the call itself
                     50: are expected to change.  It is expected to be extended with additional
                     51: facilities in future versions of the system.  In particular it is expected
                     52: that this call will be particular to a segment, and that other behaviors
                     53: such as sequential behavior will be specifiable.

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