Re: [9fans] trace.c

[Peter Bosch <pb@research.bell-labs.com>]

> trace.c came with the Jan 22 pull, but what is it?  it does show
> somewhat interesting pictures and tells me how much certain processes
> have been using the CPU, but without a man page the mind boggles :)

trace shows the kernel scheduling actions and when interrupts
occur.  it reads scheduling events from /proc/trace (unfortunately
binary format only).  the definition of a trace event can be found
in /sys/include/trace.h.

to switch on tracing:

	echo traceon > /proc/<pid>/ctl

to switch it off again:

	echo traceoff > /proc/<pid>/ctl

when real-time processes are used it also shows you the release
times and deadlines of processes.

'q'	quits trace
'+'	zooms in
'-'	zooms out
'p'	pauses trace

(hmm, i guess the above _is_ the man page ;-)).


peter.