Re: dtrace for linux

Re: dtrace for linux

[fox]

> On Sun, Apr 20, 2008 at 1:17 AM,  <fox@crisp.demon.co.uk> wrote:
> >
> >  I would like to announce that I am working on dtrace for Linux.
> >  I have the userland dtrace binary compiled, along with the first
> >  pre-pre-alpha dtracedrv.ko module loaded into my kernel.
> 
> This is great news. How will this dtrace implementation differ from
> SystemTap (http://sourceware.org/systemtap/) ?
> 
> Bart.
> 
> 

Hello Bart,


I dont know systemtap all that well, other than what i have
read on the net and browsed in the source. systemtap is similar,
but dtrace provides a high level functional language (D) and
a set of methodologies and scripts which mean learning/training
will make it easier to use.

In addition, dtrace promises to be kernel safe (whether or not it
is will be down to how good a job I do I guess!)

RE: dtrace for linux

[fox]

> >> On Sun, Apr 20, 2008 at 1:17 AM,  <fox@crisp.demon.co.uk> wrote:
> >>>
> >>>  I would like to announce that I am working on dtrace for Linux.
> >>>  I have the userland dtrace binary compiled, along with the first
> >>>  pre-pre-alpha dtracedrv.ko module loaded into my kernel.
> >> 
> >> This is great news. How will this dtrace implementation differ from
> >> SystemTap (http://sourceware.org/systemtap/) ?
> >> 
> >> Bart.
> >> 
> >> 
> >
> >Hello Bart,
> >
> >
> >I dont know systemtap all that well, other than what i have
> >read on the net and browsed in the source. systemtap is similar,
> >but dtrace provides a high level functional language (D) and
> >a set of methodologies and scripts which mean learning/training
> >will make it easier to use.
> 
> Hello,
> 
>   SystemTAP is the tool developed in order to do the same thing 
> as Dtrace. When development of SystemTAP started, Dtrace was not
>  able to be used with restriction by the license at linux. The 
> difference in both SystemTAP and Dtrace is produced by avoiding 
> being based on mounting peculiar to linux, and a license.
> 
>   By the way, aren't any ideas found in order to mitigate the 
> load when acquiring trace? If load when having taken trace as 
> for LTTng as for SystemTAP is too heavy, I feel. For example, 
> it is desirable that trace with lighter load can be taken by the
>  limiting conditions of obtaining the trace result only for 
> several seconds until panic occurs. 
> 
> Regards

I'm not really taking part in the licensing discussion - its complex,
and partially personal, and I am not in a good position to advise
either way. I am not seeking to close the source or make $$$ out of it,
so from a 'free' point of view, its something the receiver will need
to decide for themselves. At best, I am adding something to the free-pool,
and not claiming any innovation or righs over the code.

The subtle difference between systemtap and dtrace - as i see it -
is that dtrace has a well thought out language. Systemtap doesnt.
The mechanisms of both are similar at a base level, but in practise
dtrace is designed to be more 'modular'. Sun spent a lot of effort
to put the hooks in to let dtrace be effective. Some of the hooks are
available in linux - some not. So its a matter of quality of implementation.

As for performance - they are possibly similar but based on different
principals. Dtrace (like systemtap) costs nothing if you dont use it.
If you do, the performance impact depends on the quality of your
scripts (but cannot cause a kernel panic or infinite loop - in theory).
Systemtap doesnt make such guarantees. The whole raison for d'etre
for dtrace/systemtap is that when you need it, you need it *bad*. And
the minor perf hit is likely acceptable for your specific use-case.

I am not an expert in dtrace or systemtap - i have knowledge of
some aspects of both, and anything i may write on the matter may
be suspect/wrong/incorrect. I hope to correct my incorrect understandings
by virtue of this project.

BTW: progress this week has been near-zero due to a fight between
me + Ubuntu to get a custom Linus kernel to boot. Hopefully the weekend
will fare better.

-pdf

RE: dtrace for linux

[paul]

> >> On Sun, Apr 20, 2008 at 1:17 AM,  <fox@crisp.demon.co.uk> wrote:
> >>>
> >>>  I would like to announce that I am working on dtrace for Linux.
> >>>  I have the userland dtrace binary compiled, along with the first
> >>>  pre-pre-alpha dtracedrv.ko module loaded into my kernel.
> >> 
> >> This is great news. How will this dtrace implementation differ from
> >> SystemTap (http://sourceware.org/systemtap/) ?
> >> 
> >> Bart.
> >> 
> >> 
> >
> >Hello Bart,
> >
> >
> >I dont know systemtap all that well, other than what i have
> >read on the net and browsed in the source. systemtap is similar,
> >but dtrace provides a high level functional language (D) and
> >a set of methodologies and scripts which mean learning/training
> >will make it easier to use.
> 
> Hello,
> 
>   SystemTAP is the tool developed in order to do the same thing 
> as Dtrace. When development of SystemTAP started, Dtrace was not
>  able to be used with restriction by the license at linux. The 
> difference in both SystemTAP and Dtrace is produced by avoiding 
> being based on mounting peculiar to linux, and a license.
> 
>   By the way, aren't any ideas found in order to mitigate the 
> load when acquiring trace? If load when having taken trace as 
> for LTTng as for SystemTAP is too heavy, I feel. For example, 
> it is desirable that trace with lighter load can be taken by the
>  limiting conditions of obtaining the trace result only for 
> several seconds until panic occurs. 
> 
> Regards

I'm not really taking part in the licensing discussion - its complex,
and partially personal, and I am not in a good position to advise
either way. I am not seeking to close the source or make $$$ out of it,
so from a 'free' point of view, its something the receiver will need
to decide for themselves. At best, I am adding something to the free-pool,
and not claiming any innovation or righs over the code.

The subtle difference between systemtap and dtrace - as i see it -
is that dtrace has a well thought out language. Systemtap doesnt.
The mechanisms of both are similar at a base level, but in practise
dtrace is designed to be more 'modular'. Sun spent a lot of effort
to put the hooks in to let dtrace be effective. Some of the hooks are
available in linux - some not. So its a matter of quality of implementation.

As for performance - they are possibly similar but based on different
principals. Dtrace (like systemtap) costs nothing if you dont use it.
If you do, the performance impact depends on the quality of your
scripts (but cannot cause a kernel panic or infinite loop - in theory).
Systemtap doesnt make such guarantees. The whole raison for d'etre
for dtrace/systemtap is that when you need it, you need it *bad*. And
the minor perf hit is likely acceptable for your specific use-case.

I am not an expert in dtrace or systemtap - i have knowledge of
some aspects of both, and anything i may write on the matter may
be suspect/wrong/incorrect. I hope to correct my incorrect understandings
by virtue of this project.

BTW: progress this week has been near-zero due to a fight between
me + Ubuntu to get a custom Linus kernel to boot. Hopefully the weekend
will fare better.

-pdf

RE: dtrace for linux

[Takashi Nishiie]

>> On Sun, Apr 20, 2008 at 1:17 AM,  <fox@crisp.demon.co.uk> wrote:
>>>
>>>  I would like to announce that I am working on dtrace for Linux.
>>>  I have the userland dtrace binary compiled, along with the first
>>>  pre-pre-alpha dtracedrv.ko module loaded into my kernel.
>> 
>> This is great news. How will this dtrace implementation differ from
>> SystemTap (http://sourceware.org/systemtap/) ?
>> 
>> Bart.
>> 
>> 
>
>Hello Bart,
>
>
>I dont know systemtap all that well, other than what i have
>read on the net and browsed in the source. systemtap is similar,
>but dtrace provides a high level functional language (D) and
>a set of methodologies and scripts which mean learning/training
>will make it easier to use.

Hello,

  SystemTAP is the tool developed in order to do the same thing 
as Dtrace. When development of SystemTAP started, Dtrace was not
 able to be used with restriction by the license at linux. The 
difference in both SystemTAP and Dtrace is produced by avoiding 
being based on mounting peculiar to linux, and a license.

  By the way, aren't any ideas found in order to mitigate the 
load when acquiring trace? If load when having taken trace as 
for LTTng as for SystemTAP is too heavy, I feel. For example, 
it is desirable that trace with lighter load can be taken by the
 limiting conditions of obtaining the trace result only for 
several seconds until panic occurs. 

Regards

Re: dtrace for linux

[fox]

> On Sun, 20 Apr 2008, paul wrote:
> 
> > If anyone wants to grab a copy (purely for reference - dont try and run 
> > anything), you can visit
> > http://www.crisp.demon.co.uk/tools
> 
> This gives 404.
> 
> -- 
> Jiri Kosina
> SUSE Labs

Sorry - that should be tools.html:

http://www.crisp.demon.co.uk/tools.html

tx

Re: dtrace for linux

[paul]

> On Sun, 20 Apr 2008, paul wrote:
> 
> > If anyone wants to grab a copy (purely for reference - dont try and run 
> > anything), you can visit
> > http://www.crisp.demon.co.uk/tools
> 
> This gives 404.
> 
> -- 
> Jiri Kosina
> SUSE Labs

Sorry - that should be tools.html:

http://www.crisp.demon.co.uk/tools.html

tx

Re: dtrace for linux

[paul]

> On Sun, Apr 20, 2008 at 1:17 AM,  <fox@crisp.demon.co.uk> wrote:
> >
> >  I would like to announce that I am working on dtrace for Linux.
> >  I have the userland dtrace binary compiled, along with the first
> >  pre-pre-alpha dtracedrv.ko module loaded into my kernel.
> 
> This is great news. How will this dtrace implementation differ from
> SystemTap (http://sourceware.org/systemtap/) ?
> 
> Bart.
> 
> 

Hello Bart,


I dont know systemtap all that well, other than what i have
read on the net and browsed in the source. systemtap is similar,
but dtrace provides a high level functional language (D) and
a set of methodologies and scripts which mean learning/training
will make it easier to use.

In addition, dtrace promises to be kernel safe (whether or not it
is will be down to how good a job I do I guess!)

Re: dtrace for linux

[Bart Van Assche]

On Sun, Apr 20, 2008 at 1:17 AM,  <fox@crisp.demon.co.uk> wrote:
>
>  I would like to announce that I am working on dtrace for Linux.
>  I have the userland dtrace binary compiled, along with the first
>  pre-pre-alpha dtracedrv.ko module loaded into my kernel.

This is great news. How will this dtrace implementation differ from
SystemTap (http://sourceware.org/systemtap/) ?

Bart.

Re: dtrace for linux

[Jiri Kosina]

On Sun, 20 Apr 2008, paul wrote:

> If anyone wants to grab a copy (purely for reference - dont try and run 
> anything), you can visit
> http://www.crisp.demon.co.uk/tools

This gives 404.

-- 
Jiri Kosina
SUSE Labs

dtrace for linux

[paul]

I would like to announce that I am working on dtrace for Linux.
I have the userland dtrace binary compiled, along with the first
pre-pre-alpha dtracedrv.ko module loaded into my kernel.

Its early days as I work thru the issues but am into stage 3.

Stage 1 was to compile userland dtrace and stage 2 was to compile
the kernel driver. I have lots of stubs and likely bad #defines.

I am trying to improve my makefiles and header dependencies so I
can validate some aspects of kernel portability.

If anyone wants to grab a copy (purely for reference - dont try and
run anything), you can visit 

http://www.crisp.demon.co.uk/tools

and pick up a daily snapshot.

If anyone wants to contribute, feel free - especially if you
feel the approach is wrong etc.

I wont talk about licensing - except to say it will be covered
by the CDDL and not GPL, since its Sun's work and I am simply
deriving, and I am not modifying the kernel (yet).

dtrace for linux

[fox]

I would like to announce that I am working on dtrace for Linux.
I have the userland dtrace binary compiled, along with the first
pre-pre-alpha dtracedrv.ko module loaded into my kernel.

Its early days as I work thru the issues but am into stage 3.

Stage 1 was to compile userland dtrace and stage 2 was to compile
the kernel driver. I have lots of stubs and likely bad #defines.

I am trying to improve my makefiles and header dependencies so I
can validate some aspects of kernel portability.

If anyone wants to grab a copy (purely for reference - dont try and
run anything), you can visit 

http://www.crisp.demon.co.uk/tools

and pick up a daily snapshot.

If anyone wants to contribute, feel free - especially if you
feel the approach is wrong etc.

I wont talk about licensing - except to say it will be covered
by the CDDL and not GPL, since its Sun's work and I am simply
deriving, and I am not modifying the kernel (yet).

Re: DTrace for Linux

[Frank Ch. Eigler]

Valerie Henson <val_henson@linux.intel.com> writes:

> [...]  My opinion is that a port of DTrace to Linux would be
> extremely valuable, above and beyond the goals of SystemTap.  It is
> also my opinion that it will be extremely difficult. :)

Beyond the technical challenges, a legal one (SCSL-vs-GPL license
incompatibility) would at least complicate deployment of a plain port.

- FChE

Re: DTrace for Linux

[Valerie Henson]

On Tue, Mar 28, 2006 at 10:52:03PM -0800, Randy.Dunlap wrote:
> On Wed, 29 Mar 2006 11:44:47 +0530 Tushar wrote:
> 
> > Hi Guys,
> > 
> > I am planning to port DTrace (Solaris 10) utility to Linux. I have
> > done good enough research for same. Is this port of DTrace to Linux
> > already been started/completed ?
> > 
> > Please let me know your comments on this.
> 
> based on what I hear, http://sourceware.org/systemtap/
> is the Linux version...

Background: I worked for Sun in the Solaris group during DTrace's
development.  I was probably one of the first 30 people to use DTrace,
and actively used it for kernel development for over a year.

Randy didn't say this, but in case anyone got the wrong impression,
SystemTap is not a port of DTrace.  SystemTap has existed as its own
project for quite some time.  One of the current goals of SystemTap is
to provide equivalent functionality to DTrace in some areas.

My opinion is that a port of DTrace to Linux would be extremely
valuable, above and beyond the goals of SystemTap.  It is also my
opinion that it will be extremely difficult. :)

-VAL

Re: DTrace for Linux

[Randy.Dunlap]

On Wed, 29 Mar 2006 11:44:47 +0530 Tushar wrote:

> Hi Guys,
> 
> I am planning to port DTrace (Solaris 10) utility to Linux. I have
> done good enough research for same. Is this port of DTrace to Linux
> already been started/completed ?
> 
> Please let me know your comments on this.


based on what I hear, http://sourceware.org/systemtap/
is the Linux version...

---
~Randy

DTrace for Linux

[Tushar]

Hi Guys,

I am planning to port DTrace (Solaris 10) utility to Linux. I have
done good enough research for same. Is this port of DTrace to Linux
already been started/completed ?

Please let me know your comments on this.

- Tushar