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Message-ID: <162081530166.29796.5711132614441456162.tip-bot2@tip-bot2>
Date: Wed, 12 May 2021 10:28:21 -0000
From: "tip-bot2 for Peter Zijlstra" <tip-bot2@...utronix.de>
To: linux-tip-commits@...r.kernel.org
Cc: "Peter Zijlstra (Intel)" <peterz@...radead.org>,
Don Hiatt <dhiatt@...italocean.com>,
Hongyu Ning <hongyu.ning@...ux.intel.com>,
Vincent Guittot <vincent.guittot@...aro.org>, x86@...nel.org,
linux-kernel@...r.kernel.org
Subject: [tip: sched/core] sched: Trivial core scheduling cookie management
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@...radead.org>
AuthorDate: Fri, 26 Mar 2021 18:55:06 +01:00
Committer: Peter Zijlstra <peterz@...radead.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@...radead.org>
Tested-by: Don Hiatt <dhiatt@...italocean.com>
Tested-by: Hongyu Ning <hongyu.ning@...ux.intel.com>
Tested-by: Vincent Guittot <vincent.guittot@...aro.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)
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