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)