[Ksummit-2008-discuss] DTrace

Ulrich Drepper drepper at redhat.com
Sat Jun 28 20:06:03 PDT 2008


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Theodore Tso wrote:
> But if that's true, why is it that Systemtap developers haven't made
> it easy for kernel developers to install and use systemtap?

Basically everything you say is incorrect:

- - there are regular snapshots; they are done automatically every
  weekend.  They are meant to e usable

- - you need no special elfutils.  There are no API changes at all in
  the versions used in systemtap.  The patches which Roland added are
  simply not necessary for usable distributions or are adding just more
  overhead through additional tests

- - the project is simply moving fast to make "stable" releases not really
  useful.  Snapshots are meant (for now) to be the way to use the
  project

- - Insinuating that Red Hat does something evil with the releases is just
  a sign of your hostility and paranoia.  Why should RH have have any
  interest in stifling the success of the project?  As the web page
  says, snapshots should be used.  If a specific version number is
  attached to a snapshot this has no significance at all.

If you have problems getting a recent systemtap release blame your
distribution maker.  The Fedora package maintainer (who happens to be
part of the systemtap team at RH) makes releases.  Perhaps not always
frequent enough but that's something which can be discussed if
necessary.  The real problem, though, is that releases don't happen
nearly frequently enough for other distributions.


> But maybe as more people try using it, they'll discover some of these
> rough edges, and will start trying to fix it.  Every couple of months,
> I've tried using it, and because it as so many rough edges, I've
> normally found it less work to debug the kernel using manual methods
> rather trying to make Systemtap work on my system and with my kernel
> development workflow.

... and you haven't documented and reported your "rough edges"?  (I
checked the BZ database, no entry matching your addresses).

The point is that this is a tool developed mostly (almost exclusively)
by people who know development tools.  Lots of problems have been
discovered and fixed by them (including lots of problems in the debug
information generation in gcc, an ongoing project).  But there is
limited knowledge in kernel activities so the sophistication of the test
cases written by the group itself is low.  For sophisticated cases the
group relies on outside contributions.


So, if you find problems or "rough" edges, please file bugs with test
cases.

If you know parts of the kernel, consider writing tapsets to help those
who don't know that part of the kernel as well.  If you need help, post
to the systemtap mailing list.

As I mentioned before, it might indeed be the right idea to keep the
tapsets and tapscripts along with the kernel.  Kernel developers are the
best people to get this done so you won't need help with this.

- --
➧ Ulrich Drepper ➧ Red Hat, Inc. ➧ 444 Castro St ➧ Mountain View, CA ❖
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