linux-kernel.vger.kernel.org archive mirror
 help / color / mirror / Atom feed
From: Patrick Bellasi <patrick.bellasi@arm.com>
To: linux-kernel@vger.kernel.org, linux-pm@vger.kernel.org,
	linux-api@vger.kernel.org
Cc: Ingo Molnar <mingo@redhat.com>,
	Peter Zijlstra <peterz@infradead.org>, Tejun Heo <tj@kernel.org>,
	"Rafael J . Wysocki" <rafael.j.wysocki@intel.com>,
	Vincent Guittot <vincent.guittot@linaro.org>,
	Viresh Kumar <viresh.kumar@linaro.org>,
	Paul Turner <pjt@google.com>,
	Quentin Perret <quentin.perret@arm.com>,
	Dietmar Eggemann <dietmar.eggemann@arm.com>,
	Morten Rasmussen <morten.rasmussen@arm.com>,
	Juri Lelli <juri.lelli@redhat.com>, Todd Kjos <tkjos@google.com>,
	Joel Fernandes <joelaf@google.com>,
	Steve Muckle <smuckle@google.com>,
	Suren Baghdasaryan <surenb@google.com>
Subject: [PATCH v7 07/15] sched/core: uclamp: Set default clamps for RT tasks
Date: Fri,  8 Feb 2019 10:05:46 +0000	[thread overview]
Message-ID: <20190208100554.32196-8-patrick.bellasi@arm.com> (raw)
In-Reply-To: <20190208100554.32196-1-patrick.bellasi@arm.com>

By default FAIR tasks start without clamps, i.e. neither boosted nor
capped, and they run at the best frequency matching their utilization
demand.  This default behavior does not fit RT tasks which instead are
expected to run at the maximum available frequency, if not otherwise
required by explicitly capping them.

Enforce the correct behavior for RT tasks by setting util_min to max
whenever:

 1. a task is switched to the RT class and it does not already have a
    user-defined clamp value assigned.

 2. a task is forked from a parent with RESET_ON_FORK set.

NOTE: utilization clamp values are cross scheduling class attributes and
thus they are never changed/reset once a value has been explicitly
defined from user-space.

Signed-off-by: Patrick Bellasi <patrick.bellasi@arm.com>
Cc: Ingo Molnar <mingo@redhat.com>
Cc: Peter Zijlstra <peterz@infradead.org>
---
 kernel/sched/core.c | 26 ++++++++++++++++++++++++++
 1 file changed, 26 insertions(+)

diff --git a/kernel/sched/core.c b/kernel/sched/core.c
index 8b282616e9c9..569564012ddc 100644
--- a/kernel/sched/core.c
+++ b/kernel/sched/core.c
@@ -1049,6 +1049,28 @@ static int uclamp_validate(struct task_struct *p,
 static void __setscheduler_uclamp(struct task_struct *p,
 				  const struct sched_attr *attr)
 {
+	unsigned int clamp_id;
+
+	/*
+	 * On scheduling class change, reset to default clamps for tasks
+	 * without a task-specific value.
+	 */
+	for (clamp_id = 0; clamp_id < UCLAMP_CNT; ++clamp_id) {
+		unsigned int clamp_value = uclamp_none(clamp_id);
+		struct uclamp_se *uc_se = &p->uclamp[clamp_id];
+
+		/* Keep using defined clamps across class changes */
+		if (uc_se->user_defined)
+			continue;
+
+		/* By default, RT tasks always get 100% boost */
+		if (unlikely(rt_task(p) && clamp_id == UCLAMP_MIN))
+			clamp_value = uclamp_none(UCLAMP_MAX);
+
+		uc_se->bucket_id = uclamp_bucket_id(clamp_value);
+		uc_se->value = clamp_value;
+	}
+
 	if (likely(!(attr->sched_flags & SCHED_FLAG_UTIL_CLAMP)))
 		return;
 
@@ -1087,6 +1109,10 @@ static void uclamp_fork(struct task_struct *p, bool reset)
 	for (clamp_id = 0; clamp_id < UCLAMP_CNT; ++clamp_id) {
 		unsigned int clamp_value = uclamp_none(clamp_id);
 
+		/* By default, RT tasks always get 100% boost */
+		if (unlikely(rt_task(p) && clamp_id == UCLAMP_MIN))
+			clamp_value = uclamp_none(UCLAMP_MAX);
+
 		p->uclamp[clamp_id].user_defined = false;
 		p->uclamp[clamp_id].value = clamp_value;
 		p->uclamp[clamp_id].bucket_id = uclamp_bucket_id(clamp_value);
-- 
2.20.1


  parent reply	other threads:[~2019-02-08 10:06 UTC|newest]

Thread overview: 84+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2019-02-08 10:05 [PATCH v7 00/15] Add utilization clamping support Patrick Bellasi
2019-02-08 10:05 ` [PATCH v7 01/15] sched/core: uclamp: Add CPU's clamp buckets refcounting Patrick Bellasi
2019-03-12 12:52   ` Dietmar Eggemann
2019-03-13 15:15     ` Patrick Bellasi
2019-03-13 21:01       ` Suren Baghdasaryan
2019-03-14 14:54         ` Patrick Bellasi
2019-03-14 15:00       ` Patrick Bellasi
2019-03-12 15:20   ` Peter Zijlstra
2019-03-12 15:50     ` Patrick Bellasi
2019-03-13  8:19       ` Peter Zijlstra
2019-03-13 11:37         ` Patrick Bellasi
2019-03-13 13:40   ` Peter Zijlstra
2019-03-13 16:12     ` Patrick Bellasi
2019-03-13 17:22       ` Peter Zijlstra
2019-03-13 18:22         ` Patrick Bellasi
2019-03-13 19:48       ` Peter Zijlstra
2019-03-14 12:13         ` Patrick Bellasi
2019-03-14 13:32           ` Peter Zijlstra
2019-03-14 15:07             ` Patrick Bellasi
2019-03-14 19:18               ` Peter Zijlstra
2019-03-13 13:52   ` Peter Zijlstra
2019-03-13 15:59     ` Patrick Bellasi
2019-03-13 19:30       ` Peter Zijlstra
2019-03-14 11:03         ` Patrick Bellasi
2019-03-14 13:27           ` Peter Zijlstra
2019-03-13 19:39       ` Peter Zijlstra
2019-03-14 11:18         ` Patrick Bellasi
2019-03-13 21:23     ` Suren Baghdasaryan
2019-03-14 12:43       ` Patrick Bellasi
2019-03-13 14:06   ` Peter Zijlstra
2019-03-13 15:28     ` Patrick Bellasi
2019-03-13 14:09   ` Peter Zijlstra
2019-03-13 15:23     ` Patrick Bellasi
2019-03-13 19:46       ` Peter Zijlstra
2019-03-13 21:08         ` Suren Baghdasaryan
2019-03-14 12:22           ` Patrick Bellasi
2019-03-14 11:45         ` Patrick Bellasi
2019-03-13 21:32   ` Suren Baghdasaryan
2019-03-14 14:46     ` Patrick Bellasi
2019-03-14 15:29       ` Suren Baghdasaryan
2019-03-14 15:40         ` Patrick Bellasi
2019-03-14 16:39           ` Suren Baghdasaryan
2019-02-08 10:05 ` [PATCH v7 02/15] sched/core: uclamp: Enforce last task UCLAMP_MAX Patrick Bellasi
2019-03-13 14:10   ` Peter Zijlstra
2019-03-13 16:20     ` Patrick Bellasi
2019-03-13 17:29       ` Peter Zijlstra
2019-03-13 18:29         ` Patrick Bellasi
2019-03-13 14:12   ` Peter Zijlstra
2019-03-13 16:16     ` Patrick Bellasi
2019-03-14  0:29       ` Suren Baghdasaryan
2019-03-14 17:06         ` Patrick Bellasi
2019-02-08 10:05 ` [PATCH v7 03/15] sched/core: uclamp: Add system default clamps Patrick Bellasi
2019-03-13 14:32   ` Peter Zijlstra
2019-03-13 17:09     ` Patrick Bellasi
2019-03-13 19:58       ` Peter Zijlstra
2019-03-13 20:10       ` Peter Zijlstra
2019-03-15 13:41         ` Patrick Bellasi
2019-03-13 20:13   ` Peter Zijlstra
2019-03-13 20:18   ` Peter Zijlstra
2019-03-18 12:18     ` Patrick Bellasi
2019-03-18 13:10       ` Peter Zijlstra
2019-03-18 14:21         ` Patrick Bellasi
2019-03-18 14:29           ` Peter Zijlstra
2019-02-08 10:05 ` [PATCH v7 04/15] sched/core: Allow sched_setattr() to use the current policy Patrick Bellasi
2019-02-08 10:05 ` [PATCH v7 05/15] sched/core: uclamp: Extend sched_setattr() to support utilization clamping Patrick Bellasi
2019-02-08 10:05 ` [PATCH v7 06/15] sched/core: uclamp: Reset uclamp values on RESET_ON_FORK Patrick Bellasi
2019-03-13 20:52   ` Peter Zijlstra
2019-03-18 12:58     ` Patrick Bellasi
2019-02-08 10:05 ` Patrick Bellasi [this message]
2019-02-08 10:05 ` [PATCH v7 08/15] sched/cpufreq: uclamp: Add clamps for FAIR and RT tasks Patrick Bellasi
2019-02-08 10:05 ` [PATCH v7 09/15] sched/core: uclamp: Add uclamp_util_with() Patrick Bellasi
2019-02-08 10:05 ` [PATCH v7 10/15] sched/fair: uclamp: Add uclamp support to energy_compute() Patrick Bellasi
2019-03-06 17:21   ` Quentin Perret
2019-03-18 15:19     ` Patrick Bellasi
2019-02-08 10:05 ` [PATCH v7 11/15] sched/core: uclamp: Extend CPU's cgroup controller Patrick Bellasi
2019-02-14 15:48   ` Tejun Heo
2019-03-19 10:00     ` Patrick Bellasi
2019-02-08 10:05 ` [PATCH v7 12/15] sched/core: uclamp: Propagate parent clamps Patrick Bellasi
2019-03-14 16:17   ` Suren Baghdasaryan
2019-03-18 16:54     ` Patrick Bellasi
2019-03-18 16:58       ` Suren Baghdasaryan
2019-02-08 10:05 ` [PATCH v7 13/15] sched/core: uclamp: Propagate system defaults to root group Patrick Bellasi
2019-02-08 10:05 ` [PATCH v7 14/15] sched/core: uclamp: Use TG's clamps to restrict TASK's clamps Patrick Bellasi
2019-02-08 10:05 ` [PATCH v7 15/15] sched/core: uclamp: Update CPU's refcount on TG's clamp changes Patrick Bellasi

Reply instructions:

You may reply publicly to this message via plain-text email
using any one of the following methods:

* Save the following mbox file, import it into your mail client,
  and reply-to-all from there: mbox

  Avoid top-posting and favor interleaved quoting:
  https://en.wikipedia.org/wiki/Posting_style#Interleaved_style

* Reply using the --to, --cc, and --in-reply-to
  switches of git-send-email(1):

  git send-email \
    --in-reply-to=20190208100554.32196-8-patrick.bellasi@arm.com \
    --to=patrick.bellasi@arm.com \
    --cc=dietmar.eggemann@arm.com \
    --cc=joelaf@google.com \
    --cc=juri.lelli@redhat.com \
    --cc=linux-api@vger.kernel.org \
    --cc=linux-kernel@vger.kernel.org \
    --cc=linux-pm@vger.kernel.org \
    --cc=mingo@redhat.com \
    --cc=morten.rasmussen@arm.com \
    --cc=peterz@infradead.org \
    --cc=pjt@google.com \
    --cc=quentin.perret@arm.com \
    --cc=rafael.j.wysocki@intel.com \
    --cc=smuckle@google.com \
    --cc=surenb@google.com \
    --cc=tj@kernel.org \
    --cc=tkjos@google.com \
    --cc=vincent.guittot@linaro.org \
    --cc=viresh.kumar@linaro.org \
    --subject='Re: [PATCH v7 07/15] sched/core: uclamp: Set default clamps for RT tasks' \
    /path/to/YOUR_REPLY

  https://kernel.org/pub/software/scm/git/docs/git-send-email.html

* If your mail client supports setting the In-Reply-To header
  via mailto: links, try the mailto: link

This is a public inbox, see mirroring instructions
for how to clone and mirror all data and code used for this inbox;
as well as URLs for NNTP newsgroup(s).