Re: perf & rasd integration plan

[Borislav Petkov <bp@alien8.de>]

On Mon, Oct 06, 2014 at 04:12:27PM -0300, Arnaldo Carvalho de Melo wrote:
> Right, and it is being a great exercise, thanks for the patience so far
> ;-)

I know, this is your secret agenda to keep me at bay working on this! :-P

> Looking at those ifdefs we see things that are specific to tools/perf/,
> like perf_evsel having a struct hists embedded... I.e. that is of no
> interest whatsoever (so far) to rasd, and in turn pulls other object
> files.
> 
> So I think that right now we need to look at those ifdefs and go on
> making what is in tools/perf/util/ stop using it somehow, so that what
> then gets moved to tools/lib/api/perf/ (I guess this is where it should
> be, opinions?) have that sorted out.
> 
> I.e. what goes to tools/lib/api/perf/ is what is common to the needs of
> tools/perf/ and rasd (wherever it may roam).
> 
> Perhaps something like I did for sock/inet_sock/inet_connection_sock
> ages ago... I.e. the tools that want a hists will have a 
> 
> struct hists_evsel {
> 	struct perf_evsel evsel;
> 	struct hists	  hists;
> };
> 
> etc.
> 
> Experimenting with that, as it is the only thing ifdefed out in rasd's
> copy of evsel.h...

Right, this all reads like it is going in the right direction but the
more important question IMO is are we doing a libperf or are we still
doing tools/lib/api/perf/ of single object files to which people can
link?

Because if it is the second - and it sounds to me like it is - how do
you propose we link with external projects? IOW, if I want to have rasd
build *without* the kernel tree, is a simple

cp -r tools/lib/api/ <my_project>/path/to/perf/lib/

work?

I mean, I don't know and I'm just asking. Is that the proposed way? Are
we fine with that? Do we want something different, maybe even a lib? Is
it time for a lib even?

Because the whole perf functionality is being cravingly ogled by other
users - I know Matt wants it for cache QoS or whatever it is called and
there are probably a whole lot of projects which would like to process
events programatically in userspace.

So what I'm saying is, we probably should have a nice clean way
to be able to share that code with external projects instead of
external projects duplicating and building a whole library around
perf_event_open() and the likes...

Just a couple of thoughts...

-- 
Regards/Gruss,
    Boris.

Sent from a fat crate under my desk. Formatting is fine.
--