Re: [PATCH 1/2] perf: Add persistent events

[Borislav Petkov <bp@amd64.org>]

From: Arnaldo Carvalho de Melo <acme@infradead.org>
Date: Thu, Jun 17, 2010 at 11:25:46AM -0300

> Em Thu, Jun 17, 2010 at 03:43:57PM +0200, Borislav Petkov escreveu:
> > From: Arnaldo Carvalho de Melo <acme@infradead.org>
> > Date: Mon, Jun 14, 2010 at 10:02:01PM -0300
> > > > however, this does not differentiate perflib (let's call it that for how
> > > > :) from libc headers. Do we want a "perf" or "kernel" or "perflib" or
> > > > whatever prefix here - it might make sense later when this thing grows
> > > > to differentiate between the namespaces...?
> 
> > > Agreed, but the last name this thing will have will be 'perf'something :-)
> > > One of the goals at least I have with pursuing this path is to separate
> > > out everything that is not strictly 'perf' into things that can be reused
> > > by other tools, like yours.
> 
> > I'm still splitting perf/util into a more or less generic lib.  Now, I
> > want to reuse as much code as possible and am parsing the
> > "mce:mce_record" tracepoint using parse_events(). However, this means
> > that I have to push the not-so-generic perf bits like
> > util/parse-events.c into the lib. Which, in turn, pulls in
> > util/trace-event* etc.
> 
> I'm not that familiar with the trace bits in perf, but I'd say pick what
> is needed for your tool and stash it into files in a tools/lib/trace/
> directory, in a way that can be used by both perf and your tools.
> 
> I.e. no need to move files as-is, you can reorganize things to make it
> useful for both perf and your tool.

Right, this is the idea. However, all those header includes pull in
other stuff. For example, if I want to use parse_events(), it pulls in
parse-options.* which pulls in header.h, symbol.h etc.

What I ended up doing is have

tools/lib/perf/
	 /trace/
	 /include/
	 /lk/

for all the different types of facilities. So lk contains the generic
perf/util/ stuff, include contains all the linux and asm headers like
bitops.h, hash.h, kernel.h etc, perf contains parse-events.* because it
deals with perf stuff and so on.

How's that?

> > What is your preference, do we want to export all perf/util stuff for
> > other tools to use or rather link other tools together with
> > compilation modules from perf/util in case those other tools need
> > them?
> 
> If we do it on a as-needed basis, as I suggested, we go eroding the
> current perf hodgepodge of potentially generic stuff.

I think splitting it in kinda "subsystems" helps keep the modularity.

Opinions, comments?

-- 
Regards/Gruss,
Boris.

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