Re: [PATCH 5/5] tracing/ftrace: Introduce the big kernel lock tracer

["Frank Ch. Eigler" <fche at redhat dot com>]

Hi -

On Fri, Oct 24, 2008 at 10:47:36AM -0400, Steven Rostedt wrote:
> [...]
> > > I would rather prefer to use an API that provides functions/objects
> > > for most common scripting languages.
> > 
> > That is an interesting idea.  One possible problem is that the final
> > complete script "program" needs to be translated to something that can
> > run quickly and safely inside the kernel.  Full python or perl runtime
> > + libraries would have been almost certainly unbearable.
>
> Why can't the userspace application convert the script to something
> easy that the kernel can handle?

That's what we do with the systemtap script, where kernel "handling"
consists of "running the machine code".

> But have the user application interface be very simple, and perhaps
> even use perl or python.

perl and python are pretty big procedural languages, and are not
easily compiled down to compact & quickly executed machine code.  (I
take it no one is suggesting including a perl or python VM in the
kernel.)  Plus, debugger-flavoured event-handling programming style
would not look nearly as compact in perl/python as in systemtap, which
is small and domain-specific.

- FChE