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) <pet...@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)
