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 forced-newidle balancer
Date: Wed, 12 May 2021 10:28:22 -0000 [thread overview]
Message-ID: <162081530256.29796.9269859141153310893.tip-bot2@tip-bot2> (raw)
In-Reply-To: <20210422123308.800048269@infradead.org>
The following commit has been merged into the sched/core branch of tip:
Commit-ID: d2dfa17bc7de67e99685c4d6557837bf801a102c
Gitweb: https://git.kernel.org/tip/d2dfa17bc7de67e99685c4d6557837bf801a102c
Author: Peter Zijlstra <peterz@infradead.org>
AuthorDate: Tue, 17 Nov 2020 18:19:43 -05:00
Committer: Peter Zijlstra <peterz@infradead.org>
CommitterDate: Wed, 12 May 2021 11:43:30 +02:00
sched: Trivial forced-newidle balancer
When a sibling is forced-idle to match the core-cookie; search for
matching tasks to fill the core.
rcu_read_unlock() can incur an infrequent deadlock in
sched_core_balance(). Fix this by using the RCU-sched flavor instead.
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/20210422123308.800048269@infradead.org
---
include/linux/sched.h | 1 +-
kernel/sched/core.c | 130 ++++++++++++++++++++++++++++++++++++++++-
kernel/sched/idle.c | 1 +-
kernel/sched/sched.h | 6 ++-
4 files changed, 137 insertions(+), 1 deletion(-)
diff --git a/include/linux/sched.h b/include/linux/sched.h
index 45eedcc..9b822e3 100644
--- a/include/linux/sched.h
+++ b/include/linux/sched.h
@@ -705,6 +705,7 @@ struct task_struct {
#ifdef CONFIG_SCHED_CORE
struct rb_node core_node;
unsigned long core_cookie;
+ unsigned int core_occupation;
#endif
#ifdef CONFIG_CGROUP_SCHED
diff --git a/kernel/sched/core.c b/kernel/sched/core.c
index e45c1d2..b498888 100644
--- a/kernel/sched/core.c
+++ b/kernel/sched/core.c
@@ -204,6 +204,21 @@ static struct task_struct *sched_core_find(struct rq *rq, unsigned long cookie)
return __node_2_sc(node);
}
+static struct task_struct *sched_core_next(struct task_struct *p, unsigned long cookie)
+{
+ struct rb_node *node = &p->core_node;
+
+ node = rb_next(node);
+ if (!node)
+ return NULL;
+
+ p = container_of(node, struct task_struct, core_node);
+ if (p->core_cookie != cookie)
+ return NULL;
+
+ return p;
+}
+
/*
* Magic required such that:
*
@@ -5389,8 +5404,8 @@ pick_next_task(struct rq *rq, struct task_struct *prev, struct rq_flags *rf)
const struct sched_class *class;
const struct cpumask *smt_mask;
bool fi_before = false;
+ int i, j, cpu, occ = 0;
bool need_sync;
- int i, j, cpu;
if (!sched_core_enabled(rq))
return __pick_next_task(rq, prev, rf);
@@ -5512,6 +5527,9 @@ again:
if (!p)
continue;
+ if (!is_task_rq_idle(p))
+ occ++;
+
rq_i->core_pick = p;
if (rq_i->idle == p && rq_i->nr_running) {
rq->core->core_forceidle = true;
@@ -5543,6 +5561,7 @@ again:
cpu_rq(j)->core_pick = NULL;
}
+ occ = 1;
goto again;
}
}
@@ -5588,6 +5607,8 @@ again:
if (!(fi_before && rq->core->core_forceidle))
task_vruntime_update(rq_i, rq_i->core_pick, rq->core->core_forceidle);
+ rq_i->core_pick->core_occupation = occ;
+
if (i == cpu) {
rq_i->core_pick = NULL;
continue;
@@ -5609,6 +5630,113 @@ done:
return next;
}
+static bool try_steal_cookie(int this, int that)
+{
+ struct rq *dst = cpu_rq(this), *src = cpu_rq(that);
+ struct task_struct *p;
+ unsigned long cookie;
+ bool success = false;
+
+ local_irq_disable();
+ double_rq_lock(dst, src);
+
+ cookie = dst->core->core_cookie;
+ if (!cookie)
+ goto unlock;
+
+ if (dst->curr != dst->idle)
+ goto unlock;
+
+ p = sched_core_find(src, cookie);
+ if (p == src->idle)
+ goto unlock;
+
+ do {
+ if (p == src->core_pick || p == src->curr)
+ goto next;
+
+ if (!cpumask_test_cpu(this, &p->cpus_mask))
+ goto next;
+
+ if (p->core_occupation > dst->idle->core_occupation)
+ goto next;
+
+ p->on_rq = TASK_ON_RQ_MIGRATING;
+ deactivate_task(src, p, 0);
+ set_task_cpu(p, this);
+ activate_task(dst, p, 0);
+ p->on_rq = TASK_ON_RQ_QUEUED;
+
+ resched_curr(dst);
+
+ success = true;
+ break;
+
+next:
+ p = sched_core_next(p, cookie);
+ } while (p);
+
+unlock:
+ double_rq_unlock(dst, src);
+ local_irq_enable();
+
+ return success;
+}
+
+static bool steal_cookie_task(int cpu, struct sched_domain *sd)
+{
+ int i;
+
+ for_each_cpu_wrap(i, sched_domain_span(sd), cpu) {
+ if (i == cpu)
+ continue;
+
+ if (need_resched())
+ break;
+
+ if (try_steal_cookie(cpu, i))
+ return true;
+ }
+
+ return false;
+}
+
+static void sched_core_balance(struct rq *rq)
+{
+ struct sched_domain *sd;
+ int cpu = cpu_of(rq);
+
+ preempt_disable();
+ rcu_read_lock();
+ raw_spin_rq_unlock_irq(rq);
+ for_each_domain(cpu, sd) {
+ if (need_resched())
+ break;
+
+ if (steal_cookie_task(cpu, sd))
+ break;
+ }
+ raw_spin_rq_lock_irq(rq);
+ rcu_read_unlock();
+ preempt_enable();
+}
+
+static DEFINE_PER_CPU(struct callback_head, core_balance_head);
+
+void queue_core_balance(struct rq *rq)
+{
+ if (!sched_core_enabled(rq))
+ return;
+
+ if (!rq->core->core_cookie)
+ return;
+
+ if (!rq->nr_running) /* not forced idle */
+ return;
+
+ queue_balance_callback(rq, &per_cpu(core_balance_head, rq->cpu), sched_core_balance);
+}
+
static inline void sched_core_cpu_starting(unsigned int cpu)
{
const struct cpumask *smt_mask = cpu_smt_mask(cpu);
diff --git a/kernel/sched/idle.c b/kernel/sched/idle.c
index 43646e7..912b47a 100644
--- a/kernel/sched/idle.c
+++ b/kernel/sched/idle.c
@@ -437,6 +437,7 @@ static void set_next_task_idle(struct rq *rq, struct task_struct *next, bool fir
{
update_idle_core(rq);
schedstat_inc(rq->sched_goidle);
+ queue_core_balance(rq);
}
#ifdef CONFIG_SMP
diff --git a/kernel/sched/sched.h b/kernel/sched/sched.h
index 4a898ab..91ca1fe 100644
--- a/kernel/sched/sched.h
+++ b/kernel/sched/sched.h
@@ -1170,6 +1170,8 @@ static inline raw_spinlock_t *__rq_lockp(struct rq *rq)
bool cfs_prio_less(struct task_struct *a, struct task_struct *b, bool fi);
+extern void queue_core_balance(struct rq *rq);
+
#else /* !CONFIG_SCHED_CORE */
static inline bool sched_core_enabled(struct rq *rq)
@@ -1192,6 +1194,10 @@ static inline raw_spinlock_t *__rq_lockp(struct rq *rq)
return &rq->__lock;
}
+static inline void queue_core_balance(struct rq *rq)
+{
+}
+
#endif /* CONFIG_SCHED_CORE */
static inline void lockdep_assert_rq_held(struct rq *rq)
next prev parent reply other threads:[~2021-05-12 10:28 UTC|newest]
Thread overview: 103+ 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-bot2 for Peter Zijlstra [this message]
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: sched/core] " tip-bot2 for Peter Zijlstra
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
2021-08-05 16:53 ` Eugene Syromiatnikov
2021-08-05 17:00 ` Peter Zijlstra
2021-08-17 15:15 ` Eugene Syromiatnikov
2021-08-17 15:52 ` Peter Zijlstra
2021-08-17 23:17 ` Eugene Syromiatnikov
2021-08-19 11:09 ` [PATCH] sched: Fix Core-wide rq->lock for uninitialized CPUs Peter Zijlstra
2021-08-19 15:50 ` Tao Zhou
2021-08-19 16:19 ` Eugene Syromiatnikov
2021-08-20 0:18 ` Josh Don
2021-08-20 10:02 ` Peter Zijlstra
2021-08-23 9:07 ` [tip: sched/urgent] " tip-bot2 for Peter Zijlstra
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
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=162081530256.29796.9269859141153310893.tip-bot2@tip-bot2 \
--to=tip-bot2@linutronix.de \
--cc=dhiatt@digitalocean.com \
--cc=hongyu.ning@linux.intel.com \
--cc=linux-kernel@vger.kernel.org \
--cc=linux-tip-commits@vger.kernel.org \
--cc=peterz@infradead.org \
--cc=vincent.guittot@linaro.org \
--cc=x86@kernel.org \
/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
Be sure your reply has a Subject: header at the top and a blank line
before the message body.
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).