linux-kernel - Re: [PATCH v3 01/17] tools/rv: Do not skip idle in trace

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Message-ID: <20250716124105.GX1613200@noisy.programming.kicks-ass.net>
Date: Wed, 16 Jul 2025 14:41:05 +0200
From: Peter Zijlstra <peterz@...radead.org>
To: Gabriele Monaco <gmonaco@...hat.com>
Cc: linux-kernel@...r.kernel.org, Steven Rostedt <rostedt@...dmis.org>,
	linux-trace-kernel@...r.kernel.org, Ingo Molnar <mingo@...hat.com>,
	Nam Cao <namcao@...utronix.de>, Tomas Glozar <tglozar@...hat.com>,
	Juri Lelli <jlelli@...hat.com>,
	Clark Williams <williams@...hat.com>,
	John Kacur <jkacur@...hat.com>
Subject: Re: [PATCH v3 01/17] tools/rv: Do not skip idle in trace

On Wed, Jul 16, 2025 at 02:18:28PM +0200, Gabriele Monaco wrote:
> 
> 
> On Wed, 2025-07-16 at 13:50 +0200, Peter Zijlstra wrote:
> > On Tue, Jul 15, 2025 at 09:14:18AM +0200, Gabriele Monaco wrote:
> > > Currently, the userspace RV tool skips trace events triggered by
> > > the RV
> > > tool itself, this can be changed by passing the parameter -s, which
> > > sets
> > > the variable config_my_pid to 0 (instead of the tool's PID).
> > > The current condition for per-task monitors (config_has_id) does
> > > not
> > > check that config_my_pid isn't 0 to skip. In case we pass -s, we
> > > show
> > > events triggered by RV but don't show those triggered by idle (PID
> > > 0).
> > > 
> > > Fix the condition to account this scenario.
> > 
> > The distinction between !my_pid and has_id is that you can in fact
> > trace
> > pid-0 if you want?
> > 
> 
> Yes pretty much, no flag is meant to skip events from pid-0.

> > > -	if (config_has_id && (config_my_pid == id))
> > > +	if (config_my_pid && config_has_id && (config_my_pid == id))

But should we then not write:

	if (config_has_id && (config_my_pid == id))