Re: LTT user input

[Roger Luethi]

On Fri, 23 Jul 2004 18:40:26 -0400, Robert Wisniewski wrote:
>  > Looking for a common base was certainly easier before one tracing
>  > framework got merged. I don't claim to know if a common basic framework
>  > would be beneficial, but I am somewhat amazed that not more effort has
>  > gone into exploring this.
> 
> Argh.  I had up to this point been passively following this thread because
> a while ago, prior to dtrace and other such work I, Karim, and others
> invested quite of bit of effort and time responding to this group pointing
> out the benefits of performance monitoring via tracing and
> 
> IN FACT this was exactly one of the points I ardently made.  Having each
> subsystem set up their own monitoring was not only counter productive in
> terms of time and implementation effort, but prevented a unified view of
> performance from being achieved.  Nevertheless, it appears that some

This may be somewhat of a misunderstanding: You seem to be talking about
a unified framework for performance monitoring -- something I silently
assumed should be the case, while the discussion here was about various
forms of logging -- with performance monitoring being one of them.

So the question is (again, this is an issue that has been raised at the
kernel summit as well): Is there some overlap between those various
frameworks? Or do we really need completely separate frameworks for
logging time stamps (performance), auditing information, etc.?

> proclaimed by dtrace.  As Karim has pointed out in previous posts, though
> the technical concerns that were raised were addressed, it didn't seem to
> help as other nits would crop up appearing to imply that something else was
> happening.

My postings were motivated by my personal interest in better tracing
and monitoring facilities. However, I'm getting LKCD flashbacks when
reading your arguments. Which doesn't bode well.

> If indeed the remaining issue is whether there is a benefit to
> a performance monitoring infrastructure, then I wonder how you would
> interpret reactions to dtrace.

DTrace is not a performance monitoring infrastructure, so what's your
point? -- But let's assume for the sake of argument that LTT, dprobes
& Co.  provide something comparable to DTrace, and we just disagree on
what "performance monitoring" means: The chance of getting such a pile
of complexity into mainline are virtually zero (unless it's called ACPI
and required to boot some machines :-/).

So what you can push for inclusion is bound to be a subset, and the
question remains: What does such a subset, which is clearly nothing
like DTrace, offer?

Roger
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