linux-kernel - Re: heads up/RFC: 'perf trace' using ordered

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Date:	Sat, 07 Mar 2015 14:45:24 +0200
From:	Adrian Hunter <adrian.hunter@...el.com>
To:	Arnaldo Carvalho de Melo <acme@...nel.org>,
	Namhyung Kim <namhyung@...nel.org>
CC:	David Ahern <dsahern@...il.com>, Jiri Olsa <jolsa@...nel.org>,
	Ingo Molnar <mingo@...nel.org>,
	Frédéric Weisbecker <fweisbec@...il.com>,
	Linux Kernel Mailing List <linux-kernel@...r.kernel.org>
Subject: Re: heads up/RFC: 'perf trace' using ordered_events

On 4/03/2015 3:07 a.m., Arnaldo Carvalho de Melo wrote:
> Em Wed, Mar 04, 2015 at 10:01:23AM +0900, Namhyung Kim escreveu:
>> On Tue, Mar 03, 2015 at 01:49:40PM -0300, Arnaldo Carvalho de Melo wrote:
>>> Hi,
>>>
>>> 	Just a preview, but this is something David had mentioned at some
>>> point, a major problem with 'perf trace' was that it wasn't using
>>> 'perf_session' event reordering mechanism, so I've been working on making it
>>> use it, refactoring the ordered_events code so that it can be used by tools
>>> that don't deal with perf.data files.
>
>> At a conceptual level, I think event processing should be done with
>> session.  Even if perf trace does not do anything with a data file it
>> can have a (live) session like perf top does.  This way we can avoid
>
> perf top is another one I want to move away from perf_session, as it
> doesn't use any perf.data file, but needs to have events ordered.
>
> But then I really need to look at what you done in your patchset,
> probably I am missing something (or a lot).

The change appears to conflict substantially with the patches I have for
adding instruction tracing support. I will send them again soon, so you
can see what I mean.

My first thought would be that iterating over events from an event
source would be the natural abstraction which would not differentiate
from where the events came. i.e. it should not matter if the back end
is a perf.data file, pipe, or mmap.

Generally there is a need for a top level data structure. It avoids having
to use global variables and reduces the number of parameters that get
passed around.

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