Re: [PATCH] Update old Mini-HOWTO for ftrace

From: Steven Rostedt
Date: Mon Apr 06 2009 - 21:27:37 EST



On Mon, 2009-04-06 at 23:17 +0900, GeunSik Lim wrote:
> I attached patch file again because no-operation is changed
> from "none"word to "nop" word.
>
> for example,
> - "wakeup preemptirqsoff preemptoff irqsoff ftrace sched_switch none\n\n"
> + "wakeup preemptirqsoff preemptoff irqsoff function sched_switch nop\n\n"
>
> ./trace_nop.c:struct tracer nop_trace __read_mostly =
> .name = "nop",
> .init = nop_trace_init,
> .reset = nop_trace_reset,
> .selftest = trace_selftest_startup_nop,
> .flags = &nop_flags,
> .set_flag = nop_set_flag
>
>
>
> 2009/4/6 GeunSik Lim <leemgs1@xxxxxxxxx>:
> > Dear Steven,
> >
> > The author of ftrace(Internal kernel Function Tracer) feature
> > renamed the ftrace tracer
> > to function to avoid further confusion between the ftrace
> > infrastructure and the
> > function tracer on Oct-20, 2008.
> >
> > But, Update of Mini-HOWTO document are still not working
> > .
> > Most of the developers often utilize "/debug/tracing/README" file
> > as Mini-HOWTO.
> > They will confuse definition and usage about ftrace between
> > README(ftrace) file
> > and available_tracers(function) file after linux-2.6.27 like me.
> > And, I want you to append "chrt -f 5 sleep 1" command as simple
> > example for latency.
> >
> > Signed-off-by: GeunSik Lim <leemgs1@xxxxxxxxx>
> > Signed-off-by: Steven Rostedt <srostedt@xxxxxxxxxx>
> > Signed-off-by: Ingo Molnar <mingo@xxxxxxx>
> > ---
> > kernel/trace/trace.c | 3 ++-
> > 1 files changed, 2 insertions(+), 1 deletions(-)
> >
> > diff --git a/kernel/trace/trace.c b/kernel/trace/trace.c
> > index a0174a4..15f0eec 100644
> > --- a/kernel/trace/trace.c
> > +++ b/kernel/trace/trace.c
> > @@ -2358,7 +2358,7 @@ static const char readme_msg[] =
> > "# mkdir /debug\n"
> > "# mount -t debugfs nodev /debug\n\n"
> > "# cat /debug/tracing/available_tracers\n"
> > - "wakeup preemptirqsoff preemptoff irqsoff ftrace sched_switch none\n\n"
> > + "wakeup preemptirqsoff preemptoff irqsoff function
> > sched_switch none\n\n"
> > "# cat /debug/tracing/current_tracer\n"
> > "none\n"
> > "# echo sched_switch > /debug/tracing/current_tracer\n"
> > @@ -2368,6 +2368,7 @@ static const char readme_msg[] =
> > "noprint-parent nosym-offset nosym-addr noverbose\n"
> > "# echo print-parent > /debug/tracing/trace_options\n"
> > "# echo 1 > /debug/tracing/tracing_enabled\n"
> > + "# chrt -f 5 sleep 1\n"


What's the chrt for?

-- Steve


--
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majordomo@xxxxxxxxxxxxxxx
More majordomo info at http://vger.kernel.org/majordomo-info.html
Please read the FAQ at http://www.tux.org/lkml/