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SubjectRe: [PATCH 2/4] tracing: add event trace infrastructure
> On Wed, 25 Feb 2009 09:11:18 +0100 Ingo Molnar <mingo@elte.hu> wrote:
>
> >
> > * Andrew Morton <akpm@linux-foundation.org> wrote:
> >
> > > On Tue, 24 Feb 2009 23:08:56 -0500 (EST) Steven Rostedt <rostedt@goodmis.org> wrote:
> > >
> > > > > Gad, what a lot of stuff.
> > > > >
> > > > > Use strncpy_from_user()?
> > > > >
> > > > > Use strstrip()?
> > > > >
> > > > > Why do we care about leading and trailing whitespace - user error!
> > > >
> > > > This is because i want:
> > > >
> > > > cat available_events > set_event
> > > >
> > > > to work.
> > >
> > > :(
> > >
> > > Why on earth do we keep on putting all these pretty-printers
> > > and pretty-parsers into the kernel? I mean, how hard is it
> > > for userspace to read a text file, do some basic substitutions
> > > and print it out again?
> >
> > Note that there's no mandatory user-space component here - the
> > final destination is the kernel developer's eyes in 90% of the
> > cases. These traces get pasted into email, etc. etc.
> >
> > So leading spaces, meaningful formatting and general hands-on
> > usability is important. [ I know, it's a strange concept in the
> > kernel, we tend to have a perversion for the most unusable and
> > most inconsistent user interfaces ;-) ]
> >
> > It's also a balancing act. We dont want to put all of TeX into
> > the kernel obviously. Nor do we want the default to be the
> > opposite end of the spectrum: to output raw binary records. So
> > we find some middle ground. That middle ground is inluenced by
> > the developers using this stuff.
> >
>
> <For the enty enth pissing-in-the-wind time>
>
> A better approach would be to design simple, robust kernel interfaces
> which make sense and which aren't made all complex by putting the user
> interface in kernel space. And to maintain corresponding userspace
> tools which manipulate and present the IO from those kernel interfaces.
>
> But we don't do that, because userspace is hard, because we don't have
> a delivery process. But nobody has even tried! We can do this - it
> starts with `mkdir -p userspace/ktrace'.
>
> Probably it's already too late for ktrace though - that hole is already
> dug.
>
>
> Last time I pissed in this wind I got fobbed off with some stupid "put
> it in util-linux" answer. But of course we won't do that, because it's
> MUCH harder and slower and more complex than just patching the kernel
> tree. So nothing happened. Again.
>
> And please let's not all sit here busily thinking up improbable reasons
> why it can't possibly work. We're clever! We can do this sort of
> thing! If problems arise, we fix them!
>


> The only extant example I can think of is getdelays.c, and that was a
> totally half-assed effort with no infrastructural support at all. But
> quite a lot of people use it, and patches occasionally come in for it,
> no problems.

<just offtopic>

I think getdelays.c should move to "userspace/delayacct".
it's definitly not document.
(slabinfo too)

Documentation directory should only have documentation and example.





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