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Replies:
6
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Last Post:
Aug 12, 2005 3:00 PM
by: Merle Ilgenfritz
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Alexander Kolba...
akolb@eng.sun.com
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A bit of IBM anti-DTrace propaganda
Posted:
Aug 9, 2005 5:41 PM
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IBM published a 14 pages document explaining why Linux on POWER is better
than Solaris 10:
http://www-03.ibm.com/servers/enable/linux/power/pdfs/lop_vs_solaris10.pdf
Here is the bits relevant for DTrace. Hope you enjoy it as much as I did:
----------------------------------------------------------------------------- --
Although SystemTap is still a work-in-progress, its current design features are
comparable to those offered in DTrace. SystemTap will be safe and lightweight
enough to use with live production systems. It will be able to instrument both
kernel and user space programs even in the absence of source code. SystemTap's
probe language will be easy to use and users will be able to reuse general
scripts written by others.
One of the differences between SystemTap and Dtrace is that Dtrace uses an
in-kernel interpreter whereas SystemTap uses compiled native code.
Compiled native code is faster than interpreted code. Therefore, using
SystemTap will not affect the performance of the system while performing
performance measurements. The in-kernel interpreter has to be completely
bug free, otherwise problems in the interpreter itself can cause the
system to crash. Moreover, the interpreter is newly developed and not as
mature as the compiler, hence there is a higher possibility of encountering
bugs. There are a few kernel debugging features that will be supported by
SystemTap but not by Dtrace. These features include the ability to write
arbitrary locations in kernel memory and the ability to invoke arbitrary
kernel subroutines.
----------------------------------------------------------------------------- --
The last sentence is particularly entertaining. Indeed SystemTap will have
more "features" designed in!
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Posts:
4
From:
Elizaville, NY
Registered:
7/4/05
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Re: A bit of IBM anti-DTrace propaganda
Posted:
Aug 9, 2005 5:55 PM
in response to: Alexander Kolba...
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On Tue, Aug 09, 2005 at 05:41:01PM -0700, Alexander Kolbasov wrote:
> IBM published a 14 pages document explaining why Linux on POWER is better
> than Solaris 10:
>
> http://www-03.ibm.com/servers/enable/linux/power/pdfs/lop_vs_solaris10.pdf
>
> Here is the bits relevant for DTrace. Hope you enjoy it as much as I did:
>
> -------------------------------------------------------------------------------
> Although SystemTap is still a work-in-progress, its current design features are
> comparable to those offered in DTrace. SystemTap will be safe and lightweight
> enough to use with live production systems. It will be able to instrument both
> kernel and user space programs even in the absence of source code. SystemTap's
> probe language will be easy to use and users will be able to reuse general
> scripts written by others.
I like how they start talking about what SystemTap WILL BE IN THE FUTURE
here...
> One of the differences between SystemTap and Dtrace is that Dtrace uses an
> in-kernel interpreter whereas SystemTap uses compiled native code.
> Compiled native code is faster than interpreted code. Therefore, using
> SystemTap will not affect the performance of the system while performing
> performance measurements. The in-kernel interpreter has to be completely
> bug free, otherwise problems in the interpreter itself can cause the
> system to crash. Moreover, the interpreter is newly developed and not as
> mature as the compiler, hence there is a higher possibility of encountering
> bugs. There are a few kernel debugging features that will be supported by
> SystemTap but not by Dtrace. These features include the ability to write
> arbitrary locations in kernel memory and the ability to invoke arbitrary
> kernel subroutines.
> -------------------------------------------------------------------------------
...and how it's already better than DTrace here. I can almost see Captain
Contradiction rounding the corner...
Of course, our interpreter has to be completely bug-free, but their C
code doesn't. Give me a break. It's a million times easier to verify the
security of an interpreter than it is the verify the security of tens of
thousands of hand-coded probes contributed by a mass of random
developers.
> The last sentence is particularly entertaining. Indeed SystemTap will have
> more "features" designed in!
I particularly like that it's left as an excercise for the reader to write
the probes themselves.
And that it is fundamentally insecure by design: allowing full read, write
and execute access of kernel memory is ridiculous. I'll laugh when the
first SystemTap/KProbe based exploits come around and nobody can find out
what the hell is going on because they've patched SystemTap and KProbe to
``ignore'' the ``functionality.''
That their experimental code is more trustworthy than production-ready
and deployed systems code also gave me a good laugh.
Unfortunately, there are many users who will be propogating this all
over the place because they have No Clue(tm). The Joys of the Internet.
IBM, come back when you have a product that you can compare. This is
apples to cheeseburgers.
--Devon
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Posts:
3,928
From:
DE
Registered:
4/27/05
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Re: A bit of IBM anti-DTrace propaganda
Posted:
Aug 10, 2005 8:05 AM
in response to: dho
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"Devon H. O'Dell" <dodell at offmyserver dot com> wrote:
> ...and how it's already better than DTrace here. I can almost see Captain
> Contradiction rounding the corner...
>
> Of course, our interpreter has to be completely bug-free, but their C
> code doesn't. Give me a break. It's a million times easier to verify the
> security of an interpreter than it is the verify the security of tens of
> thousands of hand-coded probes contributed by a mass of random
> developers.
If you run machine code in something like dtrace, anything could happen
because there is no chance to verify the machine code. Verifying an
interpreter is easier.
Jörg
--
EMail:joerg at schily dot isdn dot cs.tu-berlin.de (home) Jörg Schilling D-13353 Berlin
js@cs.tu-berlin.de (uni)
schilling at fokus dot fraunhofer dot de (work) Blog: http://schily.blogspot.com/
URL: http://cdrecord.berlios.de/old/private/ ftp://ftp.berlios.de/pub/schily
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David Jafferian...
david.jafferian@east...
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A bit of IBM anti-DTrace propaganda
Posted:
Aug 9, 2005 8:39 PM
in response to: Alexander Kolba...
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This seems like IBM is comparing apples to oranges. SystemTap seems
to want to be more like mdb than DTrace.
Yes, "Compiled native code is faster than interpreted code." Until
you want to change it. That's why system administrators like to use
"scripting languages".
The writer also seems to be trying to make the argument that compiled
code has no probe effect when used to measure performance. As if
Heisenberg's Uncertainty Principle was null and void.
Alexander Kolbasov writes:
> IBM published a 14 pages document explaining why Linux on POWER is better
> than Solaris 10:
>
> http://www-03.ibm.com/servers/enable/linux/power/pdfs/lop_vs_solaris10.pdf
>
> Here is the bits relevant for DTrace. Hope you enjoy it as much as I did:
>
> -------------------------------------------------------------------------------
> Although SystemTap is still a work-in-progress, its current design features are
> comparable to those offered in DTrace. SystemTap will be safe and lightweight
> enough to use with live production systems. It will be able to instrument both
> kernel and user space programs even in the absence of source code. SystemTap's
> probe language will be easy to use and users will be able to reuse general
> scripts written by others.
>
> One of the differences between SystemTap and Dtrace is that Dtrace uses an
> in-kernel interpreter whereas SystemTap uses compiled native code.
> Compiled native code is faster than interpreted code. Therefore, using
> SystemTap will not affect the performance of the system while performing
> performance measurements. The in-kernel interpreter has to be completely
> bug free, otherwise problems in the interpreter itself can cause the
> system to crash. Moreover, the interpreter is newly developed and not as
> mature as the compiler, hence there is a higher possibility of encountering
> bugs. There are a few kernel debugging features that will be supported by
> SystemTap but not by Dtrace. These features include the ability to write
> arbitrary locations in kernel memory and the ability to invoke arbitrary
> kernel subroutines.
> -------------------------------------------------------------------------------
>
> The last sentence is particularly entertaining. Indeed SystemTap will have
> more "features" designed in!
>
>
> _______________________________________________
> dtrace-discuss mailing list
> dtrace-discuss at opensolaris dot org
_______________________________________________
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dtrace-discuss at opensolaris dot org
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Isaac Rozenfeld
Isaac.Rozenfeld@Sun....
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Re: A bit of IBM anti-DTrace propaganda
Posted:
Aug 10, 2005 6:10 AM
in response to: David Jafferian...
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Interesting how the author fails to reference key Dtrace features like
being able to aggregate and quantize....and, in the summary, he claims
to have introduced Dtrace ?
The Usenix Dtrace paper is referenced, but obviously not all unique
features of Dtrace
are mentioned. How, then, can a heavily worded statement such as Linux
on Power having "some, if not all, of the features provided by
DTrace " on page 4 be considered truthful ?
Isaac
----- Original Message -----
From: Richard Berlin <Richard dot Berlin at Sun dot COM>
Date: Wednesday, August 10, 2005 0:53 am
Subject: Re: [dtrace-discuss] A bit of IBM anti-DTrace propaganda
> Alexander Kolbasov wrote:
>
> >IBM published a 14 pages document explaining why Linux on POWER
> is better
> >than Solaris 10:
> >
> >http://www-
> 03.ibm.com/servers/enable/linux/power/pdfs/lop_vs_solaris10.pdf>
> >
> Wow. They are comparing our 64-bit specjbb number to their 32-bit
> number.(See pages 8 and 9.) I suppose that since we don't publish
> 32 bit
> numbers and
> they don't publish 64 bit numbers there is no way to go apples-to-
> apples.
> -- Rich
>
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Merle Ilgenfritz
merle@ilgenfritz.com
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Re: A bit of IBM anti-DTrace propaganda
Posted:
Aug 12, 2005 3:00 PM
in response to: David Jafferian...
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Hi all;
First posting here on the list.
As a Sun certified instructor, I'm enjoying all of the "insight" you guys are posting on this list. I plan on incorporating it into my Solaris 10 classes.
I looked at this IBM document and after reading all of your rebuttal's I am wondering if Sun has done an "official" response to this propaganda?
I agree with the statement:
> Unfortunately, there are many users who will be propogating this all
> over the place because they have No Clue(tm). The Joys of the Internet.
Thanks for the "enlightenment"!
Merle Ilgenfritz
Sun Certified Instructor/Course Developer/Consultant
Ilgenfritz Consulting, LLC
Exeter, RI
-------Original Message-------
> From: Devon H. O'Dell <dodell at offmyserver dot com>
> Subject: Re: [dtrace-discuss] A bit of IBM anti-DTrace propaganda
> Sent: Aug 09 '05 19:55
>
> On Tue, Aug 09, 2005 at 05:41:01PM -0700, Alexander Kolbasov wrote:
> > IBM published a 14 pages document explaining why Linux on POWER is better
> > than Solaris 10:
> >
> > http://www-03.ibm.com/servers/enable/linux/power/pdfs/lop_vs_solaris10.pdf
> >
> > Here is the bits relevant for DTrace. Hope you enjoy it as much as I did:
> >
> > -------------------------------------------------------------------------------
> > Although SystemTap is still a work-in-progress, its current design features are
> > comparable to those offered in DTrace. SystemTap will be safe and lightweight
> > enough to use with live production systems. It will be able to instrument both
> > kernel and user space programs even in the absence of source code. SystemTap's
> > probe language will be easy to use and users will be able to reuse general
> > scripts written by others.
>
> I like how they start talking about what SystemTap WILL BE IN THE FUTURE
> here...
>
> > One of the differences between SystemTap and Dtrace is that Dtrace uses an
> > in-kernel interpreter whereas SystemTap uses compiled native code.
> > Compiled native code is faster than interpreted code. Therefore, using
> > SystemTap will not affect the performance of the system while performing
> > performance measurements. The in-kernel interpreter has to be completely
> > bug free, otherwise problems in the interpreter itself can cause the
> > system to crash. Moreover, the interpreter is newly developed and not as
> > mature as the compiler, hence there is a higher possibility of encountering
> > bugs. There are a few kernel debugging features that will be supported by
> > SystemTap but not by Dtrace. These features include the ability to write
> > arbitrary locations in kernel memory and the ability to invoke arbitrary
> > kernel subroutines.
> > -------------------------------------------------------------------------------
>
> ...and how it's already better than DTrace here. I can almost see Captain
> Contradiction rounding the corner...
>
> Of course, our interpreter has to be completely bug-free, but their C
> code doesn't. Give me a break. It's a million times easier to verify the
> security of an interpreter than it is the verify the security of tens of
> thousands of hand-coded probes contributed by a mass of random
> developers.
>
> > The last sentence is particularly entertaining. Indeed SystemTap will have
> > more "features" designed in!
>
> I particularly like that it's left as an excercise for the reader to write
> the probes themselves.
>
> And that it is fundamentally insecure by design: allowing full read, write
> and execute access of kernel memory is ridiculous. I'll laugh when the
> first SystemTap/KProbe based exploits come around and nobody can find out
> what the hell is going on because they've patched SystemTap and KProbe to
> ``ignore'' the ``functionality.''
>
> That their experimental code is more trustworthy than production-ready
> and deployed systems code also gave me a good laugh.
>
> Unfortunately, there are many users who will be propogating this all
> over the place because they have No Clue(tm). The Joys of the Internet.
>
> IBM, come back when you have a product that you can compare. This is
> apples to cheeseburgers.
>
> --Devon
> _______________________________________________
> dtrace-discuss mailing list
> dtrace-discuss at opensolaris dot org
>
-------Original Message-------
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Richard Berlin
Richard.Berlin@Sun.COM
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Re: A bit of IBM anti-DTrace propaganda
Posted:
Aug 9, 2005 9:53 PM
in response to: Alexander Kolba...
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Alexander Kolbasov wrote:
>IBM published a 14 pages document explaining why Linux on POWER is better
>than Solaris 10:
>
>http://www-03.ibm.com/servers/enable/linux/power/pdfs/lop_vs_solaris10.pdf
>
>
Wow. They are comparing our 64-bit specjbb number to their 32-bit number.
(See pages 8 and 9.) I suppose that since we don't publish 32 bit
numbers and
they don't publish 64 bit numbers there is no way to go apples-to-apples.
-- Rich
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