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From: "tip-bot2 for Peter Zijlstra" <tip-bot2@linutronix.de>
To: linux-tip-commits@vger.kernel.org
Cc: "Peter Zijlstra (Intel)" <peterz@infradead.org>,
	Don Hiatt <dhiatt@digitalocean.com>,
	Hongyu Ning <hongyu.ning@linux.intel.com>,
	Vincent Guittot <vincent.guittot@linaro.org>,
	x86@kernel.org, linux-kernel@vger.kernel.org
Subject: [tip: sched/core] sched: Trivial core scheduling cookie management
Date: Wed, 12 May 2021 10:28:21 -0000
Message-ID: <162081530166.29796.5711132614441456162.tip-bot2@tip-bot2> (raw)
In-Reply-To: <20210422123308.919768100@infradead.org>

The following commit has been merged into the sched/core branch of tip:

Commit-ID:     6e33cad0af49336952e5541464bd02f5b5fd433e
Gitweb:        https://git.kernel.org/tip/6e33cad0af49336952e5541464bd02f5b5fd433e
Author:        Peter Zijlstra <peterz@infradead.org>
AuthorDate:    Fri, 26 Mar 2021 18:55:06 +01:00
Committer:     Peter Zijlstra <peterz@infradead.org>
CommitterDate: Wed, 12 May 2021 11:43:31 +02:00

sched: Trivial core scheduling cookie management

In order to not have to use pid_struct, create a new, smaller,
structure to manage task cookies for core scheduling.

Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Tested-by: Don Hiatt <dhiatt@digitalocean.com>
Tested-by: Hongyu Ning <hongyu.ning@linux.intel.com>
Tested-by: Vincent Guittot <vincent.guittot@linaro.org>
Link: https://lkml.kernel.org/r/20210422123308.919768100@infradead.org
---
 include/linux/sched.h     |   6 ++-
 kernel/fork.c             |   1 +-
 kernel/sched/Makefile     |   1 +-
 kernel/sched/core.c       |   7 +-
 kernel/sched/core_sched.c | 109 +++++++++++++++++++++++++++++++++++++-
 kernel/sched/sched.h      |  16 +++++-
 6 files changed, 137 insertions(+), 3 deletions(-)
 create mode 100644 kernel/sched/core_sched.c

diff --git a/include/linux/sched.h b/include/linux/sched.h
index 9b822e3..eab3f7c 100644
--- a/include/linux/sched.h
+++ b/include/linux/sched.h
@@ -2179,4 +2179,10 @@ int sched_trace_rq_nr_running(struct rq *rq);
 
 const struct cpumask *sched_trace_rd_span(struct root_domain *rd);
 
+#ifdef CONFIG_SCHED_CORE
+extern void sched_core_free(struct task_struct *tsk);
+#else
+static inline void sched_core_free(struct task_struct *tsk) { }
+#endif
+
 #endif
diff --git a/kernel/fork.c b/kernel/fork.c
index dc06afd..d16c60c 100644
--- a/kernel/fork.c
+++ b/kernel/fork.c
@@ -742,6 +742,7 @@ void __put_task_struct(struct task_struct *tsk)
 	exit_creds(tsk);
 	delayacct_tsk_free(tsk);
 	put_signal_struct(tsk->signal);
+	sched_core_free(tsk);
 
 	if (!profile_handoff_task(tsk))
 		free_task(tsk);
diff --git a/kernel/sched/Makefile b/kernel/sched/Makefile
index 5fc9c9b..978fcfc 100644
--- a/kernel/sched/Makefile
+++ b/kernel/sched/Makefile
@@ -36,3 +36,4 @@ obj-$(CONFIG_CPU_FREQ_GOV_SCHEDUTIL) += cpufreq_schedutil.o
 obj-$(CONFIG_MEMBARRIER) += membarrier.o
 obj-$(CONFIG_CPU_ISOLATION) += isolation.o
 obj-$(CONFIG_PSI) += psi.o
+obj-$(CONFIG_SCHED_CORE) += core_sched.o
diff --git a/kernel/sched/core.c b/kernel/sched/core.c
index b498888..55b2d93 100644
--- a/kernel/sched/core.c
+++ b/kernel/sched/core.c
@@ -167,7 +167,7 @@ static inline int rb_sched_core_cmp(const void *key, const struct rb_node *node)
 	return 0;
 }
 
-static void sched_core_enqueue(struct rq *rq, struct task_struct *p)
+void sched_core_enqueue(struct rq *rq, struct task_struct *p)
 {
 	rq->core->core_task_seq++;
 
@@ -177,14 +177,15 @@ static void sched_core_enqueue(struct rq *rq, struct task_struct *p)
 	rb_add(&p->core_node, &rq->core_tree, rb_sched_core_less);
 }
 
-static void sched_core_dequeue(struct rq *rq, struct task_struct *p)
+void sched_core_dequeue(struct rq *rq, struct task_struct *p)
 {
 	rq->core->core_task_seq++;
 
-	if (!p->core_cookie)
+	if (!sched_core_enqueued(p))
 		return;
 
 	rb_erase(&p->core_node, &rq->core_tree);
+	RB_CLEAR_NODE(&p->core_node);
 }
 
 /*
diff --git a/kernel/sched/core_sched.c b/kernel/sched/core_sched.c
new file mode 100644
index 0000000..8d0869a
--- /dev/null
+++ b/kernel/sched/core_sched.c
@@ -0,0 +1,109 @@
+// SPDX-License-Identifier: GPL-2.0-only
+
+#include "sched.h"
+
+/*
+ * A simple wrapper around refcount. An allocated sched_core_cookie's
+ * address is used to compute the cookie of the task.
+ */
+struct sched_core_cookie {
+	refcount_t refcnt;
+};
+
+unsigned long sched_core_alloc_cookie(void)
+{
+	struct sched_core_cookie *ck = kmalloc(sizeof(*ck), GFP_KERNEL);
+	if (!ck)
+		return 0;
+
+	refcount_set(&ck->refcnt, 1);
+	sched_core_get();
+
+	return (unsigned long)ck;
+}
+
+void sched_core_put_cookie(unsigned long cookie)
+{
+	struct sched_core_cookie *ptr = (void *)cookie;
+
+	if (ptr && refcount_dec_and_test(&ptr->refcnt)) {
+		kfree(ptr);
+		sched_core_put();
+	}
+}
+
+unsigned long sched_core_get_cookie(unsigned long cookie)
+{
+	struct sched_core_cookie *ptr = (void *)cookie;
+
+	if (ptr)
+		refcount_inc(&ptr->refcnt);
+
+	return cookie;
+}
+
+/*
+ * sched_core_update_cookie - replace the cookie on a task
+ * @p: the task to update
+ * @cookie: the new cookie
+ *
+ * Effectively exchange the task cookie; caller is responsible for lifetimes on
+ * both ends.
+ *
+ * Returns: the old cookie
+ */
+unsigned long sched_core_update_cookie(struct task_struct *p, unsigned long cookie)
+{
+	unsigned long old_cookie;
+	struct rq_flags rf;
+	struct rq *rq;
+	bool enqueued;
+
+	rq = task_rq_lock(p, &rf);
+
+	/*
+	 * Since creating a cookie implies sched_core_get(), and we cannot set
+	 * a cookie until after we've created it, similarly, we cannot destroy
+	 * a cookie until after we've removed it, we must have core scheduling
+	 * enabled here.
+	 */
+	SCHED_WARN_ON((p->core_cookie || cookie) && !sched_core_enabled(rq));
+
+	enqueued = sched_core_enqueued(p);
+	if (enqueued)
+		sched_core_dequeue(rq, p);
+
+	old_cookie = p->core_cookie;
+	p->core_cookie = cookie;
+
+	if (enqueued)
+		sched_core_enqueue(rq, p);
+
+	/*
+	 * If task is currently running, it may not be compatible anymore after
+	 * the cookie change, so enter the scheduler on its CPU to schedule it
+	 * away.
+	 */
+	if (task_running(rq, p))
+		resched_curr(rq);
+
+	task_rq_unlock(rq, p, &rf);
+
+	return old_cookie;
+}
+
+static unsigned long sched_core_clone_cookie(struct task_struct *p)
+{
+	unsigned long cookie, flags;
+
+	raw_spin_lock_irqsave(&p->pi_lock, flags);
+	cookie = sched_core_get_cookie(p->core_cookie);
+	raw_spin_unlock_irqrestore(&p->pi_lock, flags);
+
+	return cookie;
+}
+
+void sched_core_free(struct task_struct *p)
+{
+	sched_core_put_cookie(p->core_cookie);
+}
diff --git a/kernel/sched/sched.h b/kernel/sched/sched.h
index 3878386..904c52b 100644
--- a/kernel/sched/sched.h
+++ b/kernel/sched/sched.h
@@ -1229,6 +1229,22 @@ static inline bool sched_group_cookie_match(struct rq *rq,
 
 extern void queue_core_balance(struct rq *rq);
 
+static inline bool sched_core_enqueued(struct task_struct *p)
+{
+	return !RB_EMPTY_NODE(&p->core_node);
+}
+
+extern void sched_core_enqueue(struct rq *rq, struct task_struct *p);
+extern void sched_core_dequeue(struct rq *rq, struct task_struct *p);
+
+extern void sched_core_get(void);
+extern void sched_core_put(void);
+
+extern unsigned long sched_core_alloc_cookie(void);
+extern void sched_core_put_cookie(unsigned long cookie);
+extern unsigned long sched_core_get_cookie(unsigned long cookie);
+extern unsigned long sched_core_update_cookie(struct task_struct *p, unsigned long cookie);
+
 #else /* !CONFIG_SCHED_CORE */
 
 static inline bool sched_core_enabled(struct rq *rq)

  reply index

Thread overview: 92+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2021-04-22 12:04 [PATCH 00/19] sched: Core Scheduling Peter Zijlstra
2021-04-22 12:05 ` [PATCH 01/19] sched/fair: Add a few assertions Peter Zijlstra
2021-05-12 10:28   ` [tip: sched/core] " tip-bot2 for Peter Zijlstra
2021-05-13  8:56     ` Ning, Hongyu
2021-04-22 12:05 ` [PATCH 02/19] sched: Provide raw_spin_rq_*lock*() helpers Peter Zijlstra
2021-05-12 10:28   ` [tip: sched/core] " tip-bot2 for Peter Zijlstra
2021-04-22 12:05 ` [PATCH 03/19] sched: Wrap rq::lock access Peter Zijlstra
2021-05-12 10:28   ` [tip: sched/core] " tip-bot2 for Peter Zijlstra
2021-04-22 12:05 ` [PATCH 04/19] sched: Prepare for Core-wide rq->lock Peter Zijlstra
2021-04-24  1:22   ` Josh Don
2021-04-26  8:31     ` Peter Zijlstra
2021-04-26 22:21       ` Josh Don
2021-04-27 17:10         ` Don Hiatt
2021-04-27 23:35           ` Josh Don
2021-04-28  1:03             ` Aubrey Li
2021-04-28  6:05               ` Aubrey Li
2021-04-28 10:57                 ` Aubrey Li
2021-04-28 16:41                   ` Don Hiatt
2021-04-29 20:48                     ` Josh Don
2021-04-29 21:09                       ` Don Hiatt
2021-04-29 23:22                         ` Josh Don
2021-04-30 16:18                           ` Don Hiatt
2021-04-30  8:26                         ` Aubrey Li
2021-04-28 16:04             ` Don Hiatt
2021-04-27 23:30         ` Josh Don
2021-04-28  9:13           ` Peter Zijlstra
2021-04-28 10:35             ` Aubrey Li
2021-04-28 11:03               ` Peter Zijlstra
2021-04-28 14:18                 ` Paul E. McKenney
2021-04-29 20:11             ` Josh Don
2021-05-03 19:17               ` Peter Zijlstra
2021-04-28  7:13         ` Peter Zijlstra
2021-04-28  6:02   ` Aubrey Li
2021-04-29  8:03   ` Aubrey Li
2021-04-29 20:39     ` Josh Don
2021-04-30  8:20       ` Aubrey Li
2021-04-30  8:48         ` Josh Don
2021-04-30 14:15           ` Aubrey Li
2021-05-04  7:38       ` Peter Zijlstra
2021-05-05 16:20         ` Don Hiatt
2021-05-06 10:25           ` Peter Zijlstra
2021-05-07  9:50   ` [PATCH v2 " Peter Zijlstra
2021-05-08  8:07     ` Aubrey Li
2021-05-12  9:07       ` Peter Zijlstra
2021-04-22 12:05 ` [PATCH 05/19] sched: " Peter Zijlstra
2021-05-07  9:50   ` [PATCH v2 " Peter Zijlstra
2021-05-12 10:28     ` [tip: sched/core] " tip-bot2 for Peter Zijlstra
2021-04-22 12:05 ` [PATCH 06/19] sched: Optimize rq_lockp() usage Peter Zijlstra
2021-05-12 10:28   ` [tip: sched/core] " tip-bot2 for Peter Zijlstra
2021-04-22 12:05 ` [PATCH 07/19] sched: Allow sched_core_put() from atomic context Peter Zijlstra
2021-05-12 10:28   ` [tip: sched/core] " tip-bot2 for Peter Zijlstra
2021-04-22 12:05 ` [PATCH 08/19] sched: Introduce sched_class::pick_task() Peter Zijlstra
2021-05-12 10:28   ` [tip: sched/core] " tip-bot2 for Peter Zijlstra
2021-04-22 12:05 ` [PATCH 09/19] sched: Basic tracking of matching tasks Peter Zijlstra
2021-05-12 10:28   ` [tip: sched/core] " tip-bot2 for Peter Zijlstra
2021-04-22 12:05 ` [PATCH 10/19] sched: Add core wide task selection and scheduling Peter Zijlstra
2021-05-12 10:28   ` [tip: sched/core] " tip-bot2 for Peter Zijlstra
2021-04-22 12:05 ` [PATCH 11/19] sched/fair: Fix forced idle sibling starvation corner case Peter Zijlstra
2021-05-12 10:28   ` [tip: sched/core] " tip-bot2 for Vineeth Pillai
2021-04-22 12:05 ` [PATCH 12/19] sched: Fix priority inversion of cookied task with sibling Peter Zijlstra
2021-05-12 10:28   ` [tip: sched/core] " tip-bot2 for Joel Fernandes (Google)
2021-04-22 12:05 ` [PATCH 13/19] sched/fair: Snapshot the min_vruntime of CPUs on force idle Peter Zijlstra
2021-05-12 10:28   ` [tip: sched/core] " tip-bot2 for Joel Fernandes (Google)
2021-04-22 12:05 ` [PATCH 14/19] sched: Trivial forced-newidle balancer Peter Zijlstra
2021-05-12 10:28   ` [tip: sched/core] " tip-bot2 for Peter Zijlstra
2021-04-22 12:05 ` [PATCH 15/19] sched: Migration changes for core scheduling Peter Zijlstra
2021-05-12 10:28   ` [tip: sched/core] " tip-bot2 for Aubrey Li
2021-04-22 12:05 ` [PATCH 16/19] sched: Trivial core scheduling cookie management Peter Zijlstra
2021-05-12 10:28   ` tip-bot2 for Peter Zijlstra [this message]
2021-04-22 12:05 ` [PATCH 17/19] sched: Inherit task cookie on fork() Peter Zijlstra
2021-05-10 16:06   ` Joel Fernandes
2021-05-10 16:22     ` Chris Hyser
2021-05-10 20:47       ` Joel Fernandes
2021-05-10 21:38         ` Chris Hyser
2021-05-12  9:05           ` Peter Zijlstra
2021-05-12 20:20             ` Josh Don
2021-05-12 21:07               ` Don Hiatt
2021-05-12 10:28   ` [tip: sched/core] " tip-bot2 for Peter Zijlstra
2021-04-22 12:05 ` [PATCH 18/19] sched: prctl() core-scheduling interface Peter Zijlstra
2021-05-12 10:28   ` [tip: sched/core] " tip-bot2 for Chris Hyser
2021-06-14 23:36   ` [PATCH 18/19] " Josh Don
2021-06-15 11:31     ` Joel Fernandes
2021-04-22 12:05 ` [PATCH 19/19] kselftest: Add test for core sched prctl interface Peter Zijlstra
2021-05-12 10:28   ` [tip: sched/core] " tip-bot2 for Chris Hyser
2021-04-22 16:43 ` [PATCH 00/19] sched: Core Scheduling Don Hiatt
2021-04-22 17:29   ` Peter Zijlstra
2021-04-30  6:47 ` Ning, Hongyu
2021-05-06 10:29   ` Peter Zijlstra
2021-05-06 12:53     ` Ning, Hongyu
2021-05-07 18:02 ` Joel Fernandes
2021-05-10 16:16 ` Vincent Guittot
2021-05-11  7:00   ` Vincent Guittot

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