'\"macro stdmacro
.if n .pH g7.prf @(#)prf	40.3 of 10/10/89
.\" Copyright 1989 AT&T
.nr X
.if \nX=0 .ds x} prf 7 "System Performance Analysis Utilities" "\&"
.if \nX=1 .ds x} prf 7 "System Performance Analysis Utilities"
.if \nX=2 .ds x} prf 7 "" "\&"
.if \nX=3 .ds x} prf "" "" "\&"
.TH \*(x}
.SH NAME
\f4prf\f1 \- operating system profiler
.SH DESCRIPTION
The special file
\f4/dev/prf\fP
provides access to activity information
in the operating system.
Writing the file
loads the measurement facility with text addresses to be monitored.
Reading the file returns these 
addresses and a set of counters
indicative of activity between adjacent text addresses.
.PP
The recording mechanism is driven by the system clock
and samples the program counter at line frequency.
Samples that catch the operating system
are matched against the stored text addresses
and increment corresponding counters for later processing.
.PP
The file
\f4/dev/prf\fP
is a pseudo-device
with no associated hardware.
.SH FILES
\f4/dev/prf\fP
.SH "SEE ALSO"
\f4profiler\fP(1M).
.\"	@(#)prf.7	6.2 of 9/6/83
.Ee
