next steps

[Frank Ch. Eigler]

Hi -

On Mon, Sep 26, 2005 at 11:26:12AM -0500, Jose R. Santos wrote:

> [...]  My question really was one of simplicity and performance.
> I've looked at some of the SystemTap generated code and the size [is
> of concern] [...] What I'm interested in is if the overhead of using
> SystemTap to gather this information will be equal whether you use a
> script or a special kprobe.  [...]

I am certain that we suffer extra overhead over a hand-written C
kprobe.  After all, we include a bunch of somewhat naive checking and
debugging-enabling code.  However, looking at the relevant assembly
code, it's not *that* bad, and could be tightened in the future.

> The previous poster sort of implied that there were some performance
> issues with using SystemTap for tracing things like this.  We will
> do some performance overhead testing but I would also like to know
> if anybody has done this type of measurements already.

The system is changing rapidly enough, and we're all speculating
enough, that only individual measurements can meaningfully answer such
questions.


- FChE
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