Re: [PATCH -v2] ftrace: Documentation

[Steven Rostedt]

On Mon, 14 Jul 2008, Eric W. Biederman wrote:

>
> Steven Rostedt <rostedt@xxxxxxxxxxx> writes:
>
> > Actually it is a /debug (or /sys/mount/debug if you prefer) file.
>
> Got it.  I haven't ever actually seen anyone use debugfs.
>
> > I'd be interested in knowing who would want namespaces in traces. I've
> > basically only used tracing to see "what's happening in the kernel here?".
> > Where I only use the pid to differentiate between the tasks I know are
> > running.
>
> > Hence, tracing is much like printk. Does it really matter with these
> > outputs. But ftrace is pluggable, pid namespaces may matter in future
> > plugins.

Bare with me, I'm new to the namespace concept of pids.

>
> So it would not be hard to capture the pid namespace in mount or
> even look at current to get it (although the last is a little odd).

>From userspace or from with the kernel (doing the trace)

>
> I'm not at all certain if it makes sense.  If this is something
> an ordinary user could use then we definitely want to do something.
>
> Is tracing possible without inserting kernel modules?

The tracer is built into the kernel (no module needed).

-- Steve

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