.\" $Id$
.TH LAT_SYSCALL 8 "$Date$" "(c)1994 Larry McVoy" "LMBENCH"
.SH NAME
lat_syscall - time simple entry into the operating system
.SH SYNOPSIS
.B lat_syscall
.I "null|read|write|stat|fstat|open"
.SH DESCRIPTION
.B lat_syscall
measures how long it takes to do various simple system call
operations.  
.TP
.B null
measures how long it takes to do
.BR getppid .
This is useful as a lower bound cost on anything that has to interact
with the operating system.
.TP
.B write
measures how long it takes to write one byte to \f(CB/dev/null\fP.  
.TP
.B read
measures how long it takes to read one byte from \f(CB/dev/zero\fP.  
.TP
.B stat
measures how long it takes to 
.B stat
a file.
.TP
.B fstat
measures how long it takes to 
.B fstat
a file.
.TP
open
measures how long it takes to
.B open
and then
.B close
a file.  
Note that this does not include the time to read the directories or
inodes from disk, since everything should be in the buffer cache.
.SH OUTPUT
Output formats are:
.ft CB
.br
Simple syscall: 67 microseconds
.br
Simple write: 67 microseconds
.br
Simple read: 67 microseconds
.br
Simple stat: 67 microseconds
.br
Simple fstat: 67 microseconds
.br
Simple open/close: 67 microseconds
.ft
.SH ACKNOWLEDGEMENT
Funding for the development of
this tool was provided by Sun Microsystems Computer Corporation.
.SH "SEE ALSO"
lmbench(8), getppid(2), read(2), write(2), stat(2), fstat(2), open(2),
close(2).