Re: [RFC PATCH] libtraceevent: Increase libtraceevent logging when verbose

From: Ian Rogers <irogers@google.com>
To: Steven Rostedt <rostedt@goodmis.org>
Cc: Peter Zijlstra <peterz@infradead.org>,
	Ingo Molnar <mingo@redhat.com>,
	Arnaldo Carvalho de Melo <acme@kernel.org>,
	Mark Rutland <mark.rutland@arm.com>,
	Alexander Shishkin <alexander.shishkin@linux.intel.com>,
	Jiri Olsa <jolsa@redhat.com>, Namhyung Kim <namhyung@kernel.org>,
	linux-perf-users <linux-perf-users@vger.kernel.org>,
	LKML <linux-kernel@vger.kernel.org>,
	Linux-trace Users <linux-trace-users@vger.kernel.org>,
	Tzvetomir Stoyanov <tz.stoyanov@gmail.com>,
	Stephane Eranian <eranian@google.com>
Subject: Re: [RFC PATCH] libtraceevent: Increase libtraceevent logging when verbose
Date: Thu, 10 Jun 2021 11:50:00 -0700	[thread overview]
Message-ID: <CAP-5=fVWCpuC98O=Y3HWCEJspSMWmLwAjhBChStT4APkNboDeQ@mail.gmail.com> (raw)
In-Reply-To: <20210610103927.44462e35@oasis.local.home>

On Thu, Jun 10, 2021 at 7:39 AM Steven Rostedt <rostedt@goodmis.org> wrote:
>
> On Wed,  9 Jun 2021 23:06:43 -0700
> Ian Rogers <irogers@google.com> wrote:
>
> > libtraceevent has added more levels of debug printout and with changes
> > like:
> > https://lore.kernel.org/linux-trace-devel/20210507095022.1079364-3-tz.stoyanov@gmail.com
> > previously generated output like "registering plugin" is no longer
> > displayed. This change makes it so that if perf's verbose debug output
> > is enabled then the debug and info libtraceevent messages can be
> > displayed.
> > As this API isn't present in the deprecated tools version of
> > libtracevent I'm uploading this as an RFC.
>
> Thanks Ian,
>
> We need to start porting perf to using the upstream libtraceevent
> library. I think the best way to do that is what we did with trace-cmd.
> That is to have the make files check if the minimum version of
> libtraceevent is installed, and if so, use that instead of the local
> version. If it is not installed, produce a message encouraging the
> developer to install the upstream libtraceevent and warn that it will
> be using a deprecated older versino, then build the deprecated local
> version. After some time, we could simply remove it and make it a
> dependency, but I want to do that when all the main distros being used
> have it.
>
> Currently its in the latest Debian, Ubuntu, and Fedora. I also believe
> its in SUSE but have not checked. It's in Fedora 34, but it doesn't
> appear to be in Fedora 33. As that's not too old, I don't think we
> should make it a dependency as of yet.
>
> -- Steve

Thanks! Is there a way to do something like:

#if LIBTRACE_EVENT_API > 123
...
#endif

so that we can make sure perf is taking advantage of the improvements
in the libtraceevent API?

Ian