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Swap Device & Unix Disk Buffer

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Old 11-02-2005
Swap Device & Unix Disk Buffer
Does anyone know if when the Swap Device / Page file in unix is carrying out Page / Swap In's and Page / Swap outs, does it go through the Unix Disk Cache ( I am presuming raw partitions are not being used ) ?

Therefore if there is paging activity on a system ( measured by sar -p, sar -g and vmstat -p ), should this activity also be reflected at the Unix Disk Cache level ( measured through sar -b ) and ultamately at the disk io level ( measured through sar -d and iostat ).

Alternatively does the swap partition bypass the Unix Cache altogether ?

One other question - how does onboard disk caches ( i.e. chips embedded with the disk itself ) effect the unix cache and how do you measure this activity ?
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LEARN ABOUT MOJAVE

io::pager::page

IO::Pager::Page(3)					User Contributed Perl Documentation					IO::Pager::Page(3)

NAME

       IO::Pager::Page - Emulate IO::Page, pipe STDOUT to a pager if STDOUT is a TTY

SYNOPSIS

       Pipes STDOUT to a pager if STDOUT is a TTY

DESCRIPTION

       IO::Pager was designed to programmatically decide whether or not to point the STDOUT file handle into a pipe to program specified in the
       PAGER environment variable or one of a standard list of pagers.

USAGE

	 BEGIN {
	   use IO::Pager::Page;
	   # use I::P::P first, just in case another module sends output to STDOUT
	 }
	 print<<HEREDOC;
	 ...
	 A bunch of text later
	 HEREDOC

       If you wish to forgo the potential for a Broken Pipe foible resulting from the user exiting the pager prematurely, load IO::Pager::Page
       like so:

	 use IO::Pager::Page hush=>1;

SEE ALSO

       IO::Page, IO::Pager, IO::Pager::Unbuffered, IO::Pager::Buffered

AUTHOR

       Jerrad Pierce <jpierce@cpan.org>

       Florent Angly <florent.angly@gmail.com>

       This module inspired by Monte Mitzelfelt's IO::Page 0.02

COPYRIGHT AND LICENSE

       Copyright (C) 2003-2012 Jerrad Pierce

       o   Thou shalt not claim ownership of unmodified materials.

       o   Thou shalt not claim whole ownership of modified materials.

       o   Thou shalt grant the indemnity of the provider of materials.

       o   Thou shalt use and dispense freely without other restrictions.

       Or, if you prefer:

       This library is free software; you can redistribute it and/or modify it under the same terms as Perl itself, either Perl version 5.0 or, at
       your option, any later version of Perl 5 you may have available.

perl v5.18.2							    2012-09-04							IO::Pager::Page(3)