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=-2.2 required=3.0 tests=HEADER_FROM_DIFFERENT_DOMAINS, MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS,URIBL_BLOCKED,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 11FA6C7618B for ; Thu, 25 Jul 2019 11:41:52 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id E69FA229F9 for ; Thu, 25 Jul 2019 11:41:51 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S2404162AbfGYLls (ORCPT ); Thu, 25 Jul 2019 07:41:48 -0400 Received: from mx2.suse.de ([195.135.220.15]:58006 "EHLO mx1.suse.de" rhost-flags-OK-OK-OK-FAIL) by vger.kernel.org with ESMTP id S2404095AbfGYLlr (ORCPT ); Thu, 25 Jul 2019 07:41:47 -0400 X-Virus-Scanned: by amavisd-new at test-mx.suse.de Received: from relay2.suse.de (unknown [195.135.220.254]) by mx1.suse.de (Postfix) with ESMTP id 5F5EBAD4C; Thu, 25 Jul 2019 11:41:45 +0000 (UTC) Date: Thu, 25 Jul 2019 13:41:37 +0200 From: Michal =?iso-8859-1?Q?Koutn=FD?= To: Patrick Bellasi Cc: cgroups@vger.kernel.org, linux-api@vger.kernel.org, linux-kernel@vger.kernel.org, linux-pm@vger.kernel.org, Alessio Balsini , Dietmar Eggemann , Morten Rasmussen , Quentin Perret , Joel Fernandes , Paul Turner , Steve Muckle , Suren Baghdasaryan , Todd Kjos , Peter Zijlstra , "Rafael J . Wysocki" , Tejun Heo , Vincent Guittot , Viresh Kumar , Juri Lelli , Ingo Molnar Subject: Re: [PATCH v12 3/6] sched/core: uclamp: Propagate system defaults to root group Message-ID: <20190725114126.GA4130@blackbody.suse.cz> References: <20190718181748.28446-1-patrick.bellasi@arm.com> <20190718181748.28446-4-patrick.bellasi@arm.com> MIME-Version: 1.0 Content-Type: multipart/signed; micalg=pgp-sha256; protocol="application/pgp-signature"; boundary="wzJLGUyc3ArbnUjN" Content-Disposition: inline In-Reply-To: <20190718181748.28446-4-patrick.bellasi@arm.com> User-Agent: Mutt/1.10.1 (2018-07-13) Sender: linux-pm-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-pm@vger.kernel.org --wzJLGUyc3ArbnUjN Content-Type: text/plain; charset=us-ascii Content-Disposition: inline Content-Transfer-Encoding: quoted-printable On Thu, Jul 18, 2019 at 07:17:45PM +0100, Patrick Bellasi wrote: > The clamp values are not tunable at the level of the root task group. > That's for two main reasons: >=20 > - the root group represents "system resources" which are always > entirely available from the cgroup standpoint. >=20 > - when tuning/restricting "system resources" makes sense, tuning must > be done using a system wide API which should also be available when > control groups are not. >=20 > When a system wide restriction is available, cgroups should be aware of > its value in order to know exactly how much "system resources" are > available for the subgroups. IIUC, the global default would apply in uclamp_eff_get(), so this propagation isn't strictly necessary in order to apply to tasks (that's how it works under !CONFIG_UCLAMP_TASK_GROUP). The reason is that effective value (which isn't exposed currently) in a group takes into account this global restriction, right? > @@ -1043,12 +1063,17 @@ int sysctl_sched_uclamp_handler(struct ctl_table = *table, int write, > [...] > + if (update_root_tg) > + uclamp_update_root_tg(); > + > /* > * Updating all the RUNNABLE task is expensive, keep it simple and do > * just a lazy update at each next enqueue time. Since uclamp_update_root_tg() traverses down to uclamp_update_active_tasks() is this comment half true now? --wzJLGUyc3ArbnUjN Content-Type: application/pgp-signature; name="signature.asc" Content-Description: Digital signature -----BEGIN PGP SIGNATURE----- iQIzBAEBCAAdFiEE+amhwRV4jZeXdUhoK2l36XSZ9y4FAl05lXAACgkQK2l36XSZ 9y5cgw//QQud17T2NvswG8hJs4iqq9hLqZdoEQh3auHGt5gBhY//Pre7fKieLaeQ twqmtcup1hN8T5n1s3J88mCC/Hl7uRlvQyHj2TrN5kFbRgrPRExi6desTMWU6hGp nyfsenwH7NvPPUWlO7RhIQtRJRc23cHen01DxTWDJZrg48oeZnoJV533Sj9Qf6tV qGTj1ZikLeyPzlVvHwnP1Vb+kBIQ1VTU8dZCkV+0RW4qFtnin7nmYca57/ARC8RV KnE/DZNVETsikE/J/3dyvxw/5cJGYoZssikqIjnSrmF9eoXvWzkEnUsg2WFO6Rtl UuFllWgrPScfjBlq1KfsD4WOCGgMtiuUtaOSe3SSnH2dVALsHfgmW5pqnMC38N3O kEV1abGka6x2VTX1HJyXW/buNP5WQY2fh2dWFm06oe1iC80NiLmIULpTKZYIVdtZ LWZfAOjcXU3fwdAu8daZOKnizG0mOfQxT7PiaX/A74ucc0DV0C2JnM+MszR3pWIp huSGQ3AU4V2+OGbJPO7/rht//Du47t77tzF1RXjpjONMq8ONGIeFQ4Ansp3hSQS3 98shobgsl2Be0MUm7nWKHSOay48IoJJuZoKwvoi/rFE3Elnlbs6fcJE5IWdM3PW4 EmmxngweF0LmvVlDGLZ4JP6utbdgvGEUpJ1DUfmkKOnE4bKT60o= =lOBr -----END PGP SIGNATURE----- --wzJLGUyc3ArbnUjN--