Re: Questions regarding systemtap syntax for profiling...

["Frank Ch. Eigler" <fche at redhat dot com>]

Hi -

On Mon, Jun 06, 2005 at 10:39:48AM -0700, Spirakis, Charles wrote:

> I've been talking with Will regarding enabling profiling for system tap
> and I was wondering if you had any thoughts regarding the syntax (or
> syntax constraints) you would like to see for this area.

If you mean the probe point specification syntax, the general pattern
for these is dot-separated components; each component being an
identifier, with an optional parenthesized string or number literal.
I imagine profiling-related probe points being specified something
like these:

     kernel.time_ms(15)
     kernel.cpu(0).pmc_tlbmiss(4000)

The details don't really matter.  What matters is scoping out the
various degrees of freedom, the various options or filters that
compose naturally.

> Also, I saw in a different email thread there was a concept of
> $timestamp. What does that translate into? What type of resolution will
> it have?

Some $-variables like this will expand to whatever expressions that
make sense in kernel land, within the restricted context that probes
may run in.  We haven't listed or specified them in any detail yet.
Something generic like $timestamp may just map to (jiffies_64).


- FChE

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