Re: [PATCH] Linux Kernel Markers 0.5 for Linux 2.6.17 (with probe management)

Christoph Hellwig
2006-09-22T14:32:01Z

I hate AOL-style me-toos, but there's nothing to add to this mail.
Thanks for this coherent writeup Mathieu.

On Thu, Sep 21, 2006 at 05:42:48PM -0400, Mathieu Desnoyers wrote:
> Hi Ingo,
>
> I clearly expressed my position in the previous emails, so did you. You argued
> about a use of tracing that is not relevant to my vision of reality, which is :
>
> - Embedded systems developers won't want a breakpoint-based probe
> - High performance computing users won't want a breakpoint-based probe
> - djprobe is far away from being in an acceptable state on architectures with
> very inconvenient erratas (x86).
> - kprobe and djprobe cannot access local variables in every cases
>
> For those reasons, I prefer a jump-over-call approach which lets gcc give us the
> local variables. No need of DWARF or SystemTAP macro Kung Fu. Just C and a
> loadable module.
>
> By no means is it a replacement for a completely dynamic breakpoint-based
> instrumentation mechanism. I really think that both mechanism should coexist.
>
> This is my position : I let the distribution/user decide what is appropriate for
> their use. My goal is to provide them a flexible mechanism that takes the
> multiple variety of uses in account without performance impact if they are not
> willing to pay it to benefit from tracing.
>
> With all due respect, yes, there are Linux users different from the typical
> Redhat client. If your vision is still limited to this scope after a 500
> emails debate, I am afraid that there is very little I can do about it in
> one more.