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=-8.4 required=3.0 tests=DKIM_SIGNED,DKIM_VALID, DKIM_VALID_AU,HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI,SPF_PASS, T_DKIMWL_WL_MED,URIBL_BLOCKED,USER_IN_DEF_DKIM_WL autolearn=ham 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 DFFA1ECDE5F for ; Sun, 22 Jul 2018 03:18:02 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 8DA0520849 for ; Sun, 22 Jul 2018 03:18:02 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (2048-bit key) header.d=google.com header.i=@google.com header.b="L7/HNMDN" DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org 8DA0520849 Authentication-Results: mail.kernel.org; dmarc=fail (p=reject dis=none) header.from=google.com Authentication-Results: mail.kernel.org; spf=none smtp.mailfrom=linux-kernel-owner@vger.kernel.org Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1727417AbeGVEND (ORCPT ); Sun, 22 Jul 2018 00:13:03 -0400 Received: from mail-io0-f194.google.com ([209.85.223.194]:44233 "EHLO mail-io0-f194.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1726079AbeGVENC (ORCPT ); Sun, 22 Jul 2018 00:13:02 -0400 Received: by mail-io0-f194.google.com with SMTP id q19-v6so12937473ioh.11 for ; Sat, 21 Jul 2018 20:17:59 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=google.com; s=20161025; h=mime-version:in-reply-to:references:from:date:message-id:subject:to :cc; bh=F7xzUz2V1pBj98eAwU5jKeWQv0TkaPXyeRst1taGrrc=; b=L7/HNMDNcEIra9Ckke+8MpWC/GakpkFxo8rxf8ir3utpu8BpdMvSP6q8GGo9/yRMVJ C88R4d1j5TAmFWZ6ZLsuKX9BIAwAH/kj1NpbnEVzTUOc0Pefcxyxrf85oGiyvo2fS9un P2F0DV93CcfzYa++0Ygl1BdyFbnGivNXm/5rBrkIcMCQhuk7I8CPfOxRO5IN/2MHzXpM XIZns9YHHSaKQeQIx6WrUX1XvI/GVQDgN1eFKO0LEyWIElXv4S48gVbV2g7h2p+hJW7M 3/rTMWIJ5ysHyghly2gmeU8CVR+hLt3xV/VrTwy0dbTXlaPamudkhnAGWY7al/Eb6NWn biXg== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20161025; h=x-gm-message-state:mime-version:in-reply-to:references:from:date :message-id:subject:to:cc; bh=F7xzUz2V1pBj98eAwU5jKeWQv0TkaPXyeRst1taGrrc=; b=bHFGYxBRSb0APbQQMWuaWj51p45DsC7fC+hbDIfRyQYtyuaeH3UVYMuLbbT9hGhSxQ /V96F5BORwaiiFbCs7meho47RwF3YFYU9uRdj/SqbNoJ4HlJ4fRU4RAlhjE2M4rlTI12 qqOKNE8u6EONh/D0dIil5lnpP/xRhfzx3Na0YX02S0bQBl+YP2F7vMslRf2nM7cnmgaV NO+dJ2HYF1/OfXn4rN8K3zCOwXLkBiMpuGL0bqjOTgzSNP4A3XtY6hOXV4BcoE+21lRZ 8w7FP4OCVWrrFBjCACLClp8V/C58o9B4GFFSvG+sMWal4XfGnH1zQUwVJSNikVVdT1NS a+NQ== X-Gm-Message-State: AOUpUlFoM0A73YFhyq33KO9/omsO04X80rs4A6XFyrINVrSQnR/dMsU3 XMm29zj33RwvliPHAd+Dnm7esTgPXcaOG6BSQvwyhOBf X-Google-Smtp-Source: AAOMgpcQD6hfqNAIPsf4MtJ4COkJYLiW5rbMBzjk8Ow30gpvxkUhrvqLneHwmh5eWs4Py1LIQUspmuEWkPZLKNF9lhQ= X-Received: by 2002:a6b:fb04:: with SMTP id h4-v6mr6512340iog.193.1532229478659; Sat, 21 Jul 2018 20:17:58 -0700 (PDT) MIME-Version: 1.0 Received: by 2002:ac0:e445:0:0:0:0:0 with HTTP; Sat, 21 Jul 2018 20:17:57 -0700 (PDT) In-Reply-To: <20180716082906.6061-12-patrick.bellasi@arm.com> References: <20180716082906.6061-1-patrick.bellasi@arm.com> <20180716082906.6061-12-patrick.bellasi@arm.com> From: Suren Baghdasaryan Date: Sat, 21 Jul 2018 20:17:57 -0700 Message-ID: Subject: Re: [PATCH v2 11/12] sched/core: uclamp: update CPU's refcount on TG's clamp changes To: Patrick Bellasi Cc: linux-kernel@vger.kernel.org, linux-pm@vger.kernel.org, Ingo Molnar , Peter Zijlstra , Tejun Heo , "Rafael J . Wysocki" , Viresh Kumar , Vincent Guittot , Paul Turner , Dietmar Eggemann , Morten Rasmussen , Juri Lelli , Todd Kjos , Joel Fernandes , Steve Muckle Content-Type: text/plain; charset="UTF-8" Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Mon, Jul 16, 2018 at 1:29 AM, Patrick Bellasi wrote: > When a task group refcounts a new clamp group, we need to ensure that > the new clamp values are immediately enforced to all its tasks which are > currently RUNNABLE. This is to ensure that all currently RUNNABLE task tasks > are boosted and/or clamped as requested as soon as possible. > > Let's ensure that, whenever a new clamp group is refcounted by a task > group, all its RUNNABLE tasks are correctly accounted in their > respective CPUs. We do that by slightly refactoring uclamp_group_get() > to get an additional parameter *cgroup_subsys_state which, when > provided, it's used to walk the list of tasks in the correspond TGs and corresponding TGs > update the RUNNABLE ones. > > This is a "brute force" solution which allows to reuse the same refcount > update code already used by the per-task API. That's also the only way > to ensure a prompt enforcement of new clamp constraints on RUNNABLE > tasks, as soon as a task group attribute is tweaked. > > Signed-off-by: Patrick Bellasi > Cc: Ingo Molnar > Cc: Peter Zijlstra > Cc: Tejun Heo > Cc: Paul Turner > Cc: Todd Kjos > Cc: Joel Fernandes > Cc: Steve Muckle > Cc: Juri Lelli > Cc: Dietmar Eggemann > Cc: Morten Rasmussen > Cc: linux-kernel@vger.kernel.org > Cc: linux-pm@vger.kernel.org > --- > kernel/sched/core.c | 42 ++++++++++++++++++++++++++++++++++-------- > 1 file changed, 34 insertions(+), 8 deletions(-) > > diff --git a/kernel/sched/core.c b/kernel/sched/core.c > index 50613d3d5b83..42cff5ffddae 100644 > --- a/kernel/sched/core.c > +++ b/kernel/sched/core.c > @@ -1198,21 +1198,43 @@ static inline void uclamp_group_put(int clamp_id, int group_id) > raw_spin_unlock_irqrestore(&uc_map[group_id].se_lock, flags); > } > > +static inline void uclamp_group_get_tg(struct cgroup_subsys_state *css, > + int clamp_id, unsigned int group_id) > +{ > + struct css_task_iter it; > + struct task_struct *p; > + > + /* Update clamp groups for RUNNABLE tasks in this TG */ > + css_task_iter_start(css, 0, &it); > + while ((p = css_task_iter_next(&it))) > + uclamp_task_update_active(p, clamp_id, group_id); > + css_task_iter_end(&it); > +} > + > /** > * uclamp_group_get: increase the reference count for a clamp group > * @p: the task which clamp value must be tracked > - * @clamp_id: the clamp index affected by the task > - * @uc_se: the utilization clamp data for the task > - * @clamp_value: the new clamp value for the task > + * @css: the task group which clamp value must be tracked > + * @clamp_id: the clamp index affected by the task (group) > + * @uc_se: the utilization clamp data for the task (group) > + * @clamp_value: the new clamp value for the task (group) > * > * Each time a task changes its utilization clamp value, for a specified clamp > * index, we need to find an available clamp group which can be used to track > * this new clamp value. The corresponding clamp group index will be used by > * the task to reference count the clamp value on CPUs while enqueued. > * > + * When the cgroup's cpu controller utilization clamping support is enabled, > + * each task group has a set of clamp values which are used to restrict the > + * corresponding task specific clamp values. > + * When a clamp value for a task group is changed, all the (active) tasks > + * belonging to that task group must be update to ensure they are refcounting must be updated > + * the correct CPU's clamp value. > + * > * Return: -ENOSPC if there are no available clamp groups, 0 on success. > */ > static inline int uclamp_group_get(struct task_struct *p, > + struct cgroup_subsys_state *css, > int clamp_id, struct uclamp_se *uc_se, > unsigned int clamp_value) > { > @@ -1240,6 +1262,10 @@ static inline int uclamp_group_get(struct task_struct *p, > uc_map[next_group_id].se_count += 1; > raw_spin_unlock_irqrestore(&uc_map[next_group_id].se_lock, flags); > > + /* Newly created TG don't have tasks assigned */ > + if (css) > + uclamp_group_get_tg(css, clamp_id, next_group_id); > + > /* Update CPU's clamp group refcounts of RUNNABLE task */ > if (p) > uclamp_task_update_active(p, clamp_id, next_group_id); > @@ -1307,7 +1333,7 @@ static inline int alloc_uclamp_sched_group(struct task_group *tg, > uc_se->value = parent->uclamp[clamp_id].value; > uc_se->group_id = UCLAMP_NONE; > > - if (uclamp_group_get(NULL, clamp_id, uc_se, > + if (uclamp_group_get(NULL, NULL, clamp_id, uc_se, > parent->uclamp[clamp_id].value)) { > ret = 0; > goto out; > @@ -1362,12 +1388,12 @@ static inline int __setscheduler_uclamp(struct task_struct *p, > > /* Update min utilization clamp */ > uc_se = &p->uclamp[UCLAMP_MIN]; > - retval |= uclamp_group_get(p, UCLAMP_MIN, uc_se, > + retval |= uclamp_group_get(p, NULL, UCLAMP_MIN, uc_se, > attr->sched_util_min); > > /* Update max utilization clamp */ > uc_se = &p->uclamp[UCLAMP_MAX]; > - retval |= uclamp_group_get(p, UCLAMP_MAX, uc_se, > + retval |= uclamp_group_get(p, NULL, UCLAMP_MAX, uc_se, > attr->sched_util_max); > > mutex_unlock(&uclamp_mutex); > @@ -7274,7 +7300,7 @@ static int cpu_util_min_write_u64(struct cgroup_subsys_state *css, > > /* Update TG's reference count */ > uc_se = &tg->uclamp[UCLAMP_MIN]; > - ret = uclamp_group_get(NULL, UCLAMP_MIN, uc_se, min_value); > + ret = uclamp_group_get(NULL, css, UCLAMP_MIN, uc_se, min_value); > > out: > rcu_read_unlock(); > @@ -7306,7 +7332,7 @@ static int cpu_util_max_write_u64(struct cgroup_subsys_state *css, > > /* Update TG's reference count */ > uc_se = &tg->uclamp[UCLAMP_MAX]; > - ret = uclamp_group_get(NULL, UCLAMP_MAX, uc_se, max_value); > + ret = uclamp_group_get(NULL, css, UCLAMP_MAX, uc_se, max_value); > > out: > rcu_read_unlock(); > -- > 2.17.1 >