Tuesday, 4 October 2011

Dtrace on linux and Oracle?

Great news today - everyone is talking about Oracle shipping DTrace
on the next Oracle Linux release.

Whilst Oracle are not seen as the great open-source giver-aways,
this can only be good.

I have no inside knowledge on DTrace for Oracle, and twitter (http://twitter.com/#!/search/%23dtrace)
has references to people rejoicing or denouncing it.

Is dtrace battle hardened for production use? No. One person
isnt going to prove that DTrace works everywhere for everyone on every
kernel version. I have tried; one gets bogged down in details, especially
for legacy releases and the myriads of distros that have inconsistent
packages and package names.

It works (mostly) for me; I know it crashes on a 16-core box occasionally.
(Alas, I dont have a 16-core box. Maybe its the 48GB of RAM which is the
issue rather than the number of cores, which affects the page table
layout of that system).

As anyone knows who manages software projects, a software project
manager probably does little "coding" .. the closer to completion
of the project, the harder and more required it is to reach
100% perfection. Ask Linus. I dont know how much real coding vs
patching/merging/overseeing he does.

Even the big-guns out there, like RedHat and Oracle - much of the
time and expense is tracking down bugs. There are a few people
who add value. This is what software engineering is about. Finding
your place, and managing those around you to optimise delivery.

I dont know what Oracle is doing; even if its a closed-wall, there
are benefits. When Apple introduced DTrace, it did a great job of
allowing them to fix and optimise and understand their own systems. Sure,
it wasnt perfect in the early days.

So, lets see if Oracle can influence.

From what I read, Adam Leventhal has been experimenting with
adding kernel probes to the Linux source. Even if this is the only
thing he has done, then its a great news banner. I'm loathe to walk
that plank knowing that maintaining such deltas is difficult when you
are not a part of a key release. Maybe if Ubuntu or RedHat or someone
would offer to allow such merges in, it would be fun to add them.

Solaris has hundreds/thousands of probe points, added over the last
5+ years. Each would have required consideration about what to measure,
whether the correct probes were in the right places, and supporting/testing
them. Probe-dropping is laborious and nobody will thank you for
those probes. A lot of people will benefit when "it just works".

So, lets see what happens.

And why have I been quiet recently? Well, various other mini projects
needed to be addressed. "proc" is one of them; I am not happy with it as
yet - sometimes the results seem to be suspicious, but it does look good.

But my recent project is to update CRiSP a little. Now it is supporting
grids/gridlines, so you can see the true structure of a file.

Keep watching.

Post created by CRiSP v10.0.15a-b6064

1 comment:

  1. In order to implement this, wouldn't Oracle have to use a similar method that you have been using implementing DTrace as a kernel module to avoid CDDL vs. GPL licensing conflicts?

    If so, then would this halt your own DTrace work?