From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-2.3 required=3.0 tests=HEADER_FROM_DIFFERENT_DOMAINS, MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS,USER_AGENT_SANE_1 autolearn=no autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id F311CC47404 for ; Wed, 2 Oct 2019 19:10:29 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id D93A8222D3 for ; Wed, 2 Oct 2019 19:10:29 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1729866AbfJBTK2 (ORCPT ); Wed, 2 Oct 2019 15:10:28 -0400 Received: from atrey.karlin.mff.cuni.cz ([195.113.26.193]:47194 "EHLO atrey.karlin.mff.cuni.cz" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1729835AbfJBTK2 (ORCPT ); Wed, 2 Oct 2019 15:10:28 -0400 Received: by atrey.karlin.mff.cuni.cz (Postfix, from userid 512) id 45C75802F8; Wed, 2 Oct 2019 21:10:10 +0200 (CEST) Date: Wed, 2 Oct 2019 21:10:23 +0200 From: Pavel Machek To: Matthias Kaehlcke Cc: Steven Rostedt , "Rafael J . Wysocki" , Kevin Hilman , Ulf Hansson , Len Brown , Greg Kroah-Hartman , Ingo Molnar , Douglas Anderson , linux-pm@vger.kernel.org, Amit Kucheria , linux-kernel@vger.kernel.org, Ravi Chandra Sadineni Subject: Re: [PATCH v1] PM / Domains: Add tracepoints Message-ID: <20191002191023.GD13492@amd> References: <20190926150406.v1.1.I07a769ad7b00376777c9815fb169322cde7b9171@changeid> <20190927044239.589e7c4c@oasis.local.home> <20191001163542.GB87296@google.com> <20191001130343.4480afe3@gandalf.local.home> <20191001174235.GC87296@google.com> <20191001140846.65d7866c@gandalf.local.home> <20191001193701.GD87296@google.com> MIME-Version: 1.0 Content-Type: multipart/signed; micalg=pgp-sha1; protocol="application/pgp-signature"; boundary="EY/WZ/HvNxOox07X" Content-Disposition: inline In-Reply-To: <20191001193701.GD87296@google.com> User-Agent: Mutt/1.5.23 (2014-03-12) Sender: linux-pm-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-pm@vger.kernel.org --EY/WZ/HvNxOox07X Content-Type: text/plain; charset=us-ascii Content-Disposition: inline Content-Transfer-Encoding: quoted-printable On Tue 2019-10-01 12:37:01, Matthias Kaehlcke wrote: > On Tue, Oct 01, 2019 at 02:08:46PM -0400, Steven Rostedt wrote: > > On Tue, 1 Oct 2019 10:42:35 -0700 > > Matthias Kaehlcke wrote: > >=20 > > > On Tue, Oct 01, 2019 at 01:03:43PM -0400, Steven Rostedt wrote: > > > > On Tue, 1 Oct 2019 09:35:42 -0700 > > > > Matthias Kaehlcke wrote: > > > > =20 > > > > > How about this instead: > > > > >=20 > > > > > Add tracepoints for genpd_power_on, genpd_power_off and > > > > > genpd_set_performance_state. The tracepoints can help with > > > > > understanding power domain behavior of a given device, which > > > > > may be particularly interesting for battery powered devices > > > > > and suspend/resume. =20 > > > >=20 > > > > Do you have a use case example to present? =20 > > >=20 > > > TBH I'm not looking into a specific use case right now. While > > > peeking around in /sys/kernel/debug/tracing/events to learn more > > > about existing tracepoints that might be relevant for my work > > > I noticed the absence of genpd ones and it seemed a good idea to > > > add them preemptively. Conceptually they seem similar to the > > > existing regulator_enable/disable and cpu_idle tracepoints. > > >=20 > > > As an abstract use case I could see power analysis on battery > > > powered devices during suspend. genpd_power_on/off allow to see > > > which power domains remain on during suspend, and might give > > > insights for possible power saving options. Examples could be that > > > a power domain stays unexpectedly on due to a misconfiguration, or > > > two power domains remain on when it could be only one if you just > > > moved that one pin/port over to the other domain in the next > > > hardware revision. > >=20 > > If the power management maintainers have no issues with adding these, > > then neither do I ;-) It would be them who would pull them in anyway. >=20 > Ok, I'll send a new version with the changes you suggested and some more > info in the commit message, unless PM maintainers raise concerns before > that. Dunno. Adding tracepoints because someone might need them for, umm, something... I'd wait until they are actually needed. Best regards, Pavel --=20 (english) http://www.livejournal.com/~pavelmachek (cesky, pictures) http://atrey.karlin.mff.cuni.cz/~pavel/picture/horses/blo= g.html --EY/WZ/HvNxOox07X Content-Type: application/pgp-signature; name="signature.asc" Content-Description: Digital signature -----BEGIN PGP SIGNATURE----- Version: GnuPG v1 iEUEARECAAYFAl2U9h8ACgkQMOfwapXb+vJlCgCXdBSL7hbDfn+LcSCp5VzPLAl6 fQCaA5CKSoT22nF69BPs91zdN1eNR6I= =lSwj -----END PGP SIGNATURE----- --EY/WZ/HvNxOox07X--