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.

AUTHOR

Carl Staelin and Larry McVoy

Comments, suggestions, and bug reports are always welcome.