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Annotation of researchv10dc/man/manb/vadvise.2v, revision 1.1.1.1

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

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