Re: [RFC PATCH 03/23] sched/core: Initialize the class of a new task

From: Ricardo Neri <ricardo.neri-calderon@linux.intel.com>
To: Peter Zijlstra <peterz@infradead.org>
Cc: Joel Fernandes <joel@joelfernandes.org>,
	Juri Lelli <juri.lelli@redhat.com>,
	Vincent Guittot <vincent.guittot@linaro.org>,
	Ricardo Neri <ricardo.neri@intel.com>,
	"Ravi V. Shankar" <ravi.v.shankar@intel.com>,
	Ben Segall <bsegall@google.com>,
	Daniel Bristot de Oliveira <bristot@redhat.com>,
	Dietmar Eggemann <dietmar.eggemann@arm.com>,
	Len Brown <len.brown@intel.com>, Mel Gorman <mgorman@suse.de>,
	"Rafael J. Wysocki" <rafael.j.wysocki@intel.com>,
	Srinivas Pandruvada <srinivas.pandruvada@linux.intel.com>,
	Steven Rostedt <rostedt@goodmis.org>,
	Tim Chen <tim.c.chen@linux.intel.com>,
	Valentin Schneider <vschneid@redhat.com>,
	x86@kernel.org, linux-kernel@vger.kernel.org,
	"Tim C . Chen" <tim.c.chen@intel.com>
Subject: Re: [RFC PATCH 03/23] sched/core: Initialize the class of a new task
Date: Sat, 1 Oct 2022 13:32:41 -0700	[thread overview]
Message-ID: <20221001203241.GA14536@ranerica-svr.sc.intel.com> (raw)
In-Reply-To: <YzL053SxqWUimANi@hirez.programming.kicks-ass.net>

On Tue, Sep 27, 2022 at 03:04:39PM +0200, Peter Zijlstra wrote:
> On Mon, Sep 26, 2022 at 02:57:29PM +0000, Joel Fernandes wrote:
> 
> > > +#ifdef CONFIG_SCHED_TASK_CLASSES
> > > +	p->class			= TASK_CLASS_UNCLASSIFIED;
> > > +#endif
> > 
> > I find the term 'class' very broad and unclear what kind of class (without
> > further reading). So I am worried about how this generic term usage plays
> > with Linux source code in the long-term (like what if someone else comes up
> > with a usage of term 'class' that is unrelated to IPC.)
> 
> However much I like making a pain for people using C++ to compile the
> kernel, I do think ipcc might be better here
> (instructions_per_cycle_class for those of the novel per identifier
> school of thought).

Sure, I will use ippc
> 
> > To that end, I was wondering if it could be renamed to p->ipc_class, and
> > CONFIG_SCHED_TASK_IPC_CLASSES, or something.
> 
> Can we *please* shorten those thing instead of writing a novel?
> CONFIG_SCHED_IPC_CLASS works just as well, no? Or TASK_IPC, whatever.

... and avoid the novel-style identifiers :) .

Thanks and BR,
Ricardo