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LAT_PAGEFAULT(8)                    LMBENCH                   LAT_PAGEFAULT(8)


NAME

       lat_pagefault - measure the cost of pagefaulting pages from a file


SYNOPSIS

       lat_pagefault [ -P <parallelism> ] [ -W <warmups> ] [ -N <repetitions>
       ] file [ file....  ]


DESCRIPTION

       lat_pagefault times how fast a page of a file can be faulted in.  The
       file is flushed from (local) memory by using the msync() interface with
       the invalidate flag set.  (Note that NFS does not send this over the
       wire so this makes for a handy way to measure the cost of going across
       the wire.)

       The benchmark maps in the entire file and the access pages backwards
       using a stride of 256K kilobytes.


OUTPUT

       Output format is below; it prints the average cost of page faulting a
       page.

       Pagefaults on <file>: <d> usecs


BUGS

       Using a stride of 256K may be a bad idea because SCSI controllers may
       have caches bigger than that.


ACKNOWLEDGEMENT

       Funding for the development of this tool was provided by Sun
       Microsystems Computer Corporation.


SEE ALSO

       lmbench(8).


AUTHOR

       Carl Staelin and Larry McVoy

       Comments, suggestions, and bug reports are always welcome.

(c)1994 Larry McVoy                 $Date$                    LAT_PAGEFAULT(8)

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