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More DTrace envy

More DTrace envy

Posted Jul 3, 2008 13:16 UTC (Thu) by SEJeff (subscriber, #51588)
Parent article: More DTrace envy

@Jake, the article writer:
How can you mention SystemTap's lack of userspace tracing support when it does support this
feature? Roland McGrath of redhat is working on a new ptrace() named utrace[1]. Using utrace,
someone created a project named uprobes [2]. Using uprobes, tapsets including userspace
tracing were written at [3].

Roland made grumbles of submitting utrace for mainline again not so long ago. Once utrace is
in mainline we will soon see full userspace + kernelspace tracing support in SystemTap. The
systemtap + utrace userspace tracing support was put into RHEL5.2 beta [4].

So please get the facts straight. While it would be *REALLY NICE* if sun were to allow DTrace
in Linux by relicensing it gplv2, that doesn't look like it will happen.

So eventually...
Linux's answer to DTrace = SystemTap + uprobes
Linux's answer to ZFS = btrfs

As fast as things are developing we aren't a long way off. This isn't fud, only facts people.


[1] http://people.redhat.com/roland/utrace/2.6-current/
[2] http://ols.108.redhat.com/2007/Reprints/keniston-Reprint.pdf
[3] http://lwn.net/Articles/255429/
[4] http://www.redhat.com/archives/rhelv5-announce/2008-March... CTRL F SystemTap


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User-space probes

Posted Jul 3, 2008 13:55 UTC (Thu) by corbet (editor, #1) [Link]

Perhaps Jake was watching the discussion, where the systemtap developers talked about their work toward having user-space probes in the future? If I wanted to run systemtap with any sort of user-space probing now - especially if I wanted to take advantage of all those nice probe points already put into applications like postgresql - I'd be pretty much out of luck. I think Jake has his facts straight enough.

More DTrace envy

Posted Jul 3, 2008 20:30 UTC (Thu) by oak (guest, #2786) [Link]

> As fast as things are developing we aren't a long way off. This isn't 
fud, only facts people.

I don't want to be pessimistic, but Utrace seems still work in progress, 
only the very first patchset from it has gotten to upstream, it supports 
well only x86 & powerPC and rest of it's still being designed.  See the 
latest status report:
http://www.redhat.com/archives/utrace-devel/2008-July/mht...

I think it's at least a year until it's fully (API stabilized etc) in 
upstream kernel with Systemtap supporting it well, a good set of tapsets, 
useful scripts, documentation and some GUIs (Mortadelo and Stapgui lack a 
lot of things).

This is what Apple is already doing with DTrace:
http://developer.apple.com/documentation/developertools/C...

And before that their developers already had Shark (which AFAIK doesn't 
use DTrace):
http://developer.apple.com/tools/performance/optimizingwi...

Btw. the Tracing Summit in Canada earlier this year produced fairly good 
overview of the state of tracing tools currently (also elsewhere than on 
x86):
https://ltt.polymtl.ca/tracingwiki/index.php/TracingBook

More DTrace envy

Posted Jul 10, 2008 5:23 UTC (Thu) by renox (subscriber, #23785) [Link]

Probably because the author know the state of the user tracing where DTrace support has
been/is being incorporated in many tools: Ruby, etc which simplify a lot the tracing by the
end-user..

Whereas currently SystemTap doesn't have this 'support' of all the enduser tools.

>we aren't a long way off.

Depends of your measurements! If you look at Ted Tso complaints, support of SystemTap by
endusers tools, the schedule, SystemTap appears to be very, very late compared to DTrace..


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