.TH TRACE 1
.SH NAME
trace \- show (real-time) process behavior
.SH SYNOPSIS
.B trace
[
.B \-d
.I profdev
]
[
.B \-v
]
[
.B \-w
]
[pid ... ]
.SH DESCRIPTION
.I Trace
displays the behavior of processes running on the machine.  In its
window it shows a time line for each traced process.  Running
processes are shown as colored blocks.  When a process is scheduled as
a real-time process, black up arrows indicate process releases, black
down arrows indicate process deadlines, red down arrows indicate the
process ran over its allotted scheduled time, and green down arrows to
indicates a process yielded the processor before its deadline.
Non-real-time processes do not have such release times and deadlines
and no real-time information is shown for such processes.
.PP
Trace reads /proc/trace to retrieve trace events from the kernel
scheduler.  Trace events are binary data structures, which are
generated by the kernel scheduler whenever a noteworthy event occurs.
The
.B \-d
flag can be used to specify another trace file.
.PP
The
.B \-v
flag prints out the events as they are received from the event file.
.PP
The \-w
flag makes
.B trace
open a new window for its display.
.PP
To enable process tracing echo the string "trace on" into 
/proc/<pid>/ctl.  To disable tracing of a process echo "trace off"
in the control file.  Trace enables tracing on all processes as specified
by their
.B pids 
.PP
The following one-character commands are recognized by
.BR trace :
.TP
.B +
Zoom in by a factor of two,
.TP
.B -
Zoom out by a factor of two,
.TP
.B p
Pause or resume,
.TP
.B q
Quit.
.SH "SEE ALSO
.IR proc (3)
.SH FILES
.TF 
.TP
.B /proc/trace
trace event file
.TP
.B /sys/include/trace.h
trace event data structures
.TP
.SH SOURCE
.B /sys/src/cmd/trace