linux-kernel.vger.kernel.org archive mirror
 help / color / mirror / Atom feed
From: Peter Zijlstra <peterz@infradead.org>
To: joel@joelfernandes.org, chris.hyser@oracle.com,
	joshdon@google.com, mingo@kernel.org, vincent.guittot@linaro.org,
	valentin.schneider@arm.com, mgorman@suse.de
Cc: linux-kernel@vger.kernel.org, peterz@infradead.org,
	tj@kernel.org, tglx@linutronix.de
Subject: [PATCH 3/9] sched: Trivial core scheduling cookie management
Date: Thu, 01 Apr 2021 15:10:15 +0200	[thread overview]
Message-ID: <20210401133917.231259659@infradead.org> (raw)
In-Reply-To: <20210401131012.395311786@infradead.org>

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>
---
 include/linux/sched.h     |    6 ++
 kernel/fork.c             |    1 
 kernel/sched/Makefile     |    1 
 kernel/sched/core.c       |    7 +--
 kernel/sched/core_sched.c |  106 ++++++++++++++++++++++++++++++++++++++++++++++
 kernel/sched/sched.h      |   16 ++++++
 6 files changed, 134 insertions(+), 3 deletions(-)

--- a/include/linux/sched.h
+++ b/include/linux/sched.h
@@ -2169,4 +2169,10 @@ int sched_trace_rq_nr_running(struct 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
--- a/kernel/fork.c
+++ b/kernel/fork.c
@@ -737,6 +737,7 @@ void __put_task_struct(struct task_struc
 	exit_creds(tsk);
 	delayacct_tsk_free(tsk);
 	put_signal_struct(tsk->signal);
+	sched_core_free(tsk);
 
 	if (!profile_handoff_task(tsk))
 		free_task(tsk);
--- a/kernel/sched/Makefile
+++ b/kernel/sched/Makefile
@@ -36,3 +36,4 @@ obj-$(CONFIG_CPU_FREQ_GOV_SCHEDUTIL) +=
 obj-$(CONFIG_MEMBARRIER) += membarrier.o
 obj-$(CONFIG_CPU_ISOLATION) += isolation.o
 obj-$(CONFIG_PSI) += psi.o
+obj-$(CONFIG_SCHED_CORE) += core_sched.o
--- a/kernel/sched/core.c
+++ b/kernel/sched/core.c
@@ -157,7 +157,7 @@ static inline int rb_sched_core_cmp(cons
 	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++;
 
@@ -167,14 +167,15 @@ static void sched_core_enqueue(struct rq
 	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);
 }
 
 /*
--- /dev/null
+++ b/kernel/sched/core_sched.c
@@ -0,0 +1,106 @@
+// 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 - Common helper to update a task's core cookie. This
+ * updates the selected cookie field.
+ * @p: The task whose cookie should be updated.
+ * @cookie: The new cookie.
+ * @cookie_type: The cookie field to which the cookie corresponds.
+ */
+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);
+}
--- a/kernel/sched/sched.h
+++ b/kernel/sched/sched.h
@@ -1222,6 +1222,22 @@ static inline bool sched_group_cookie_ma
 
 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)



  parent reply	other threads:[~2021-04-01 18:21 UTC|newest]

Thread overview: 36+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2021-04-01 13:10 [PATCH 0/9] sched: Core scheduling interfaces Peter Zijlstra
2021-04-01 13:10 ` [PATCH 1/9] sched: Allow sched_core_put() from atomic context Peter Zijlstra
2021-04-01 13:10 ` [PATCH 2/9] sched: Implement core-sched assertions Peter Zijlstra
2021-04-01 13:10 ` Peter Zijlstra [this message]
2021-04-01 20:04   ` [PATCH 3/9] sched: Trivial core scheduling cookie management Josh Don
2021-04-02  7:13     ` Peter Zijlstra
2021-04-01 13:10 ` [PATCH 4/9] sched: Default core-sched policy Peter Zijlstra
2021-04-21 13:33   ` Peter Zijlstra
2021-04-21 14:31     ` Chris Hyser
2021-04-01 13:10 ` [PATCH 5/9] sched: prctl() core-scheduling interface Peter Zijlstra
2021-04-07 17:00   ` Peter Zijlstra
2021-04-18  3:52     ` Joel Fernandes
2021-04-01 13:10 ` [PATCH 6/9] kselftest: Add test for core sched prctl interface Peter Zijlstra
2021-04-01 13:10 ` [PATCH 7/9] sched: Cgroup core-scheduling interface Peter Zijlstra
2021-04-02  0:34   ` Josh Don
2021-04-01 13:10 ` [PATCH 8/9] rbtree: Remove const from the rb_find_add() comparator Peter Zijlstra
2021-04-01 13:10 ` [PATCH 9/9] sched: prctl() and cgroup interaction Peter Zijlstra
2021-04-03  1:30   ` Josh Don
2021-04-06 15:12     ` Peter Zijlstra
2021-04-04 23:39 ` [PATCH 0/9] sched: Core scheduling interfaces Tejun Heo
2021-04-05 18:46   ` Joel Fernandes
2021-04-06 14:16     ` Tejun Heo
2021-04-18  1:35       ` Joel Fernandes
2021-04-19  9:00         ` Peter Zijlstra
2021-04-21 13:35           ` Peter Zijlstra
2021-04-21 14:45             ` Chris Hyser
2021-04-06 15:32   ` Peter Zijlstra
2021-04-06 16:08     ` Tejun Heo
2021-04-07 18:39       ` Peter Zijlstra
2021-04-07 16:50   ` Michal Koutný
2021-04-07 18:34     ` Peter Zijlstra
2021-04-08 13:25       ` Michal Koutný
2021-04-08 15:02         ` Peter Zijlstra
2021-04-09  0:16           ` Josh Don
2021-04-19 11:30       ` Tejun Heo
2021-04-20  1:17         ` Josh Don

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=20210401133917.231259659@infradead.org \
    --to=peterz@infradead.org \
    --cc=chris.hyser@oracle.com \
    --cc=joel@joelfernandes.org \
    --cc=joshdon@google.com \
    --cc=linux-kernel@vger.kernel.org \
    --cc=mgorman@suse.de \
    --cc=mingo@kernel.org \
    --cc=tglx@linutronix.de \
    --cc=tj@kernel.org \
    --cc=valentin.schneider@arm.com \
    --cc=vincent.guittot@linaro.org \
    --subject='Re: [PATCH 3/9] sched: Trivial core scheduling cookie management' \
    /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).