Re: [PATCH 2/4] tracing: add event trace infrastructure

From: Ingo Molnar
Date: Wed Feb 25 2009 - 03:14:08 EST



* Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx> wrote:

> On Tue, 24 Feb 2009 23:08:56 -0500 (EST) Steven Rostedt <rostedt@xxxxxxxxxxx> 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.

Ingo
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