graphene/LibOS/shim/test/apps/lmbench/lmbench-2.5/doc/clock.8

.\" $Id$
.TH CLOCK 8 "$Date$" "(c)1994 Larry McVoy" "LMBENCH"
.SH NAME
clock \- report timing attributes
.SH SYNOPSIS
.B clock
.SH DESCRIPTION
.B clock
reports the timing interval, 
.BR ENOUGH ,
timing overhead
.BR TIMING_OVERHEAD ,
and loop overhead
.BR LOOP_OVERHEAD .
The required timing interval is determined experimentally to
ensure that the timing results are accurate to within 1% in
the spite of the system clock resolution and measurement 
overheads.  
It is necessary to measure
.B ENOUGH
experimentally because system clock resolution varies widely
across systems, from as large as 10 milliseconds to as small as
1 microsecond, a range of four orders of magnitude.
The timing overheads and loop overheads are used by the 
timing harness
.I timing(3)
to remove the various overheads from the measured times.
.SH OUTPUT
The various results are reported in micro-seconds, e.g.,
.IP ""
\fCENOUGH=5000
.br
TIMING_OVERHEAD=7.000000
.br
LOOP_OVERHEAD=0.000004
.br
# version 2.0\fR
.ft
.SH ACKNOWLEDGEMENT
Funding for the development of
this tool was provided by Sun Microsystems Computer Corporation.
.SH "SEE ALSO"
lmbench(8), lmbench(3), timing(3).