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From: Will Deacon <will@kernel.org>
To: linux-arm-kernel@lists.infradead.org
Cc: linux-arch@vger.kernel.org, linux-kernel@vger.kernel.org,
	Will Deacon <will@kernel.org>,
	Catalin Marinas <catalin.marinas@arm.com>,
	Marc Zyngier <maz@kernel.org>,
	Greg Kroah-Hartman <gregkh@linuxfoundation.org>,
	Peter Zijlstra <peterz@infradead.org>,
	Morten Rasmussen <morten.rasmussen@arm.com>,
	Qais Yousef <qais.yousef@arm.com>,
	Suren Baghdasaryan <surenb@google.com>,
	Quentin Perret <qperret@google.com>, Tejun Heo <tj@kernel.org>,
	Johannes Weiner <hannes@cmpxchg.org>,
	Ingo Molnar <mingo@redhat.com>,
	Juri Lelli <juri.lelli@redhat.com>,
	Vincent Guittot <vincent.guittot@linaro.org>,
	"Rafael J. Wysocki" <rjw@rjwysocki.net>,
	Dietmar Eggemann <dietmar.eggemann@arm.com>,
	Daniel Bristot de Oliveira <bristot@redhat.com>,
	Valentin Schneider <valentin.schneider@arm.com>,
	Mark Rutland <mark.rutland@arm.com>,
	kernel-team@android.com
Subject: [PATCH v9 08/20] cpuset: Cleanup cpuset_cpus_allowed_fallback() use in select_fallback_rq()
Date: Tue,  8 Jun 2021 19:03:01 +0100	[thread overview]
Message-ID: <20210608180313.11502-9-will@kernel.org> (raw)
In-Reply-To: <20210608180313.11502-1-will@kernel.org>

select_fallback_rq() only needs to recheck for an allowed CPU if the
affinity mask of the task has changed since the last check.

Return a 'bool' from cpuset_cpus_allowed_fallback() to indicate whether
the affinity mask was updated, and use this to elide the allowed check
when the mask has been left alone.

No functional change.

Suggested-by: Valentin Schneider <valentin.schneider@arm.com>
Signed-off-by: Will Deacon <will@kernel.org>
---
 include/linux/cpuset.h |  5 +++--
 kernel/cgroup/cpuset.c | 10 ++++++++--
 kernel/sched/core.c    |  3 +--
 3 files changed, 12 insertions(+), 6 deletions(-)

diff --git a/include/linux/cpuset.h b/include/linux/cpuset.h
index 414a8e694413..d2b9c41c8edf 100644
--- a/include/linux/cpuset.h
+++ b/include/linux/cpuset.h
@@ -59,7 +59,7 @@ extern void cpuset_wait_for_hotplug(void);
 extern void cpuset_read_lock(void);
 extern void cpuset_read_unlock(void);
 extern void cpuset_cpus_allowed(struct task_struct *p, struct cpumask *mask);
-extern void cpuset_cpus_allowed_fallback(struct task_struct *p);
+extern bool cpuset_cpus_allowed_fallback(struct task_struct *p);
 extern nodemask_t cpuset_mems_allowed(struct task_struct *p);
 #define cpuset_current_mems_allowed (current->mems_allowed)
 void cpuset_init_current_mems_allowed(void);
@@ -188,8 +188,9 @@ static inline void cpuset_cpus_allowed(struct task_struct *p,
 	cpumask_copy(mask, task_cpu_possible_mask(p));
 }
 
-static inline void cpuset_cpus_allowed_fallback(struct task_struct *p)
+static inline bool cpuset_cpus_allowed_fallback(struct task_struct *p)
 {
+	return false;
 }
 
 static inline nodemask_t cpuset_mems_allowed(struct task_struct *p)
diff --git a/kernel/cgroup/cpuset.c b/kernel/cgroup/cpuset.c
index 4e7c271e3800..a6bab2259f98 100644
--- a/kernel/cgroup/cpuset.c
+++ b/kernel/cgroup/cpuset.c
@@ -3327,17 +3327,22 @@ void cpuset_cpus_allowed(struct task_struct *tsk, struct cpumask *pmask)
  * which will not contain a sane cpumask during cases such as cpu hotplugging.
  * This is the absolute last resort for the scheduler and it is only used if
  * _every_ other avenue has been traveled.
+ *
+ * Returns true if the affinity of @tsk was changed, false otherwise.
  **/
 
-void cpuset_cpus_allowed_fallback(struct task_struct *tsk)
+bool cpuset_cpus_allowed_fallback(struct task_struct *tsk)
 {
 	const struct cpumask *cs_mask;
+	bool changed = false;
 	const struct cpumask *possible_mask = task_cpu_possible_mask(tsk);
 
 	rcu_read_lock();
 	cs_mask = task_cs(tsk)->cpus_allowed;
-	if (is_in_v2_mode() && cpumask_subset(cs_mask, possible_mask))
+	if (is_in_v2_mode() && cpumask_subset(cs_mask, possible_mask)) {
 		do_set_cpus_allowed(tsk, cs_mask);
+		changed = true;
+	}
 	rcu_read_unlock();
 
 	/*
@@ -3357,6 +3362,7 @@ void cpuset_cpus_allowed_fallback(struct task_struct *tsk)
 	 * select_fallback_rq() will fix things ups and set cpu_possible_mask
 	 * if required.
 	 */
+	return changed;
 }
 
 void __init cpuset_init_current_mems_allowed(void)
diff --git a/kernel/sched/core.c b/kernel/sched/core.c
index 0c1b6f1a6c91..9e75cb3fbc9c 100644
--- a/kernel/sched/core.c
+++ b/kernel/sched/core.c
@@ -2779,8 +2779,7 @@ static int select_fallback_rq(int cpu, struct task_struct *p)
 		/* No more Mr. Nice Guy. */
 		switch (state) {
 		case cpuset:
-			if (IS_ENABLED(CONFIG_CPUSETS)) {
-				cpuset_cpus_allowed_fallback(p);
+			if (cpuset_cpus_allowed_fallback(p)) {
 				state = possible;
 				break;
 			}
-- 
2.32.0.rc1.229.g3e70b5a671-goog


WARNING: multiple messages have this Message-ID
From: Will Deacon <will@kernel.org>
To: linux-arm-kernel@lists.infradead.org
Cc: linux-arch@vger.kernel.org, linux-kernel@vger.kernel.org,
	Will Deacon <will@kernel.org>,
	Catalin Marinas <catalin.marinas@arm.com>,
	Marc Zyngier <maz@kernel.org>,
	Greg Kroah-Hartman <gregkh@linuxfoundation.org>,
	Peter Zijlstra <peterz@infradead.org>,
	Morten Rasmussen <morten.rasmussen@arm.com>,
	Qais Yousef <qais.yousef@arm.com>,
	Suren Baghdasaryan <surenb@google.com>,
	Quentin Perret <qperret@google.com>, Tejun Heo <tj@kernel.org>,
	Johannes Weiner <hannes@cmpxchg.org>,
	Ingo Molnar <mingo@redhat.com>,
	Juri Lelli <juri.lelli@redhat.com>,
	Vincent Guittot <vincent.guittot@linaro.org>,
	"Rafael J. Wysocki" <rjw@rjwysocki.net>,
	Dietmar Eggemann <dietmar.eggemann@arm.com>,
	Daniel Bristot de Oliveira <bristot@redhat.com>,
	Valentin Schneider <valentin.schneider@arm.com>,
	Mark Rutland <mark.rutland@arm.com>,
	kernel-team@android.com
Subject: [PATCH v9 08/20] cpuset: Cleanup cpuset_cpus_allowed_fallback() use in select_fallback_rq()
Date: Tue,  8 Jun 2021 19:03:01 +0100	[thread overview]
Message-ID: <20210608180313.11502-9-will@kernel.org> (raw)
In-Reply-To: <20210608180313.11502-1-will@kernel.org>

select_fallback_rq() only needs to recheck for an allowed CPU if the
affinity mask of the task has changed since the last check.

Return a 'bool' from cpuset_cpus_allowed_fallback() to indicate whether
the affinity mask was updated, and use this to elide the allowed check
when the mask has been left alone.

No functional change.

Suggested-by: Valentin Schneider <valentin.schneider@arm.com>
Signed-off-by: Will Deacon <will@kernel.org>
---
 include/linux/cpuset.h |  5 +++--
 kernel/cgroup/cpuset.c | 10 ++++++++--
 kernel/sched/core.c    |  3 +--
 3 files changed, 12 insertions(+), 6 deletions(-)

diff --git a/include/linux/cpuset.h b/include/linux/cpuset.h
index 414a8e694413..d2b9c41c8edf 100644
--- a/include/linux/cpuset.h
+++ b/include/linux/cpuset.h
@@ -59,7 +59,7 @@ extern void cpuset_wait_for_hotplug(void);
 extern void cpuset_read_lock(void);
 extern void cpuset_read_unlock(void);
 extern void cpuset_cpus_allowed(struct task_struct *p, struct cpumask *mask);
-extern void cpuset_cpus_allowed_fallback(struct task_struct *p);
+extern bool cpuset_cpus_allowed_fallback(struct task_struct *p);
 extern nodemask_t cpuset_mems_allowed(struct task_struct *p);
 #define cpuset_current_mems_allowed (current->mems_allowed)
 void cpuset_init_current_mems_allowed(void);
@@ -188,8 +188,9 @@ static inline void cpuset_cpus_allowed(struct task_struct *p,
 	cpumask_copy(mask, task_cpu_possible_mask(p));
 }
 
-static inline void cpuset_cpus_allowed_fallback(struct task_struct *p)
+static inline bool cpuset_cpus_allowed_fallback(struct task_struct *p)
 {
+	return false;
 }
 
 static inline nodemask_t cpuset_mems_allowed(struct task_struct *p)
diff --git a/kernel/cgroup/cpuset.c b/kernel/cgroup/cpuset.c
index 4e7c271e3800..a6bab2259f98 100644
--- a/kernel/cgroup/cpuset.c
+++ b/kernel/cgroup/cpuset.c
@@ -3327,17 +3327,22 @@ void cpuset_cpus_allowed(struct task_struct *tsk, struct cpumask *pmask)
  * which will not contain a sane cpumask during cases such as cpu hotplugging.
  * This is the absolute last resort for the scheduler and it is only used if
  * _every_ other avenue has been traveled.
+ *
+ * Returns true if the affinity of @tsk was changed, false otherwise.
  **/
 
-void cpuset_cpus_allowed_fallback(struct task_struct *tsk)
+bool cpuset_cpus_allowed_fallback(struct task_struct *tsk)
 {
 	const struct cpumask *cs_mask;
+	bool changed = false;
 	const struct cpumask *possible_mask = task_cpu_possible_mask(tsk);
 
 	rcu_read_lock();
 	cs_mask = task_cs(tsk)->cpus_allowed;
-	if (is_in_v2_mode() && cpumask_subset(cs_mask, possible_mask))
+	if (is_in_v2_mode() && cpumask_subset(cs_mask, possible_mask)) {
 		do_set_cpus_allowed(tsk, cs_mask);
+		changed = true;
+	}
 	rcu_read_unlock();
 
 	/*
@@ -3357,6 +3362,7 @@ void cpuset_cpus_allowed_fallback(struct task_struct *tsk)
 	 * select_fallback_rq() will fix things ups and set cpu_possible_mask
 	 * if required.
 	 */
+	return changed;
 }
 
 void __init cpuset_init_current_mems_allowed(void)
diff --git a/kernel/sched/core.c b/kernel/sched/core.c
index 0c1b6f1a6c91..9e75cb3fbc9c 100644
--- a/kernel/sched/core.c
+++ b/kernel/sched/core.c
@@ -2779,8 +2779,7 @@ static int select_fallback_rq(int cpu, struct task_struct *p)
 		/* No more Mr. Nice Guy. */
 		switch (state) {
 		case cpuset:
-			if (IS_ENABLED(CONFIG_CPUSETS)) {
-				cpuset_cpus_allowed_fallback(p);
+			if (cpuset_cpus_allowed_fallback(p)) {
 				state = possible;
 				break;
 			}
-- 
2.32.0.rc1.229.g3e70b5a671-goog


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  parent reply	other threads:[~2021-06-08 18:04 UTC|newest]

Thread overview: 50+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2021-06-08 18:02 [PATCH v9 00/20] Add support for 32-bit tasks on asymmetric AArch32 systems Will Deacon
2021-06-08 18:02 ` Will Deacon
2021-06-08 18:02 ` [PATCH v9 01/20] arm64: cpuinfo: Split AArch32 registers out into a separate struct Will Deacon
2021-06-08 18:02   ` Will Deacon
2021-06-08 18:02 ` [PATCH v9 02/20] arm64: Allow mismatched 32-bit EL0 support Will Deacon
2021-06-08 18:02   ` Will Deacon
2021-06-08 18:02 ` [PATCH v9 03/20] KVM: arm64: Kill 32-bit vCPUs on systems with mismatched " Will Deacon
2021-06-08 18:02   ` Will Deacon
2021-06-08 18:02 ` [PATCH v9 04/20] arm64: Kill 32-bit applications scheduled on 64-bit-only CPUs Will Deacon
2021-06-08 18:02   ` Will Deacon
2021-06-08 18:02 ` [PATCH v9 05/20] sched: Introduce task_cpu_possible_mask() to limit fallback rq selection Will Deacon
2021-06-08 18:02   ` Will Deacon
2021-06-08 18:02 ` [PATCH v9 06/20] cpuset: Don't use the cpu_possible_mask as a last resort for cgroup v1 Will Deacon
2021-06-08 18:02   ` Will Deacon
2021-06-10 12:59   ` Valentin Schneider
2021-06-10 12:59     ` Valentin Schneider
2021-06-08 18:03 ` [PATCH v9 07/20] cpuset: Honour task_cpu_possible_mask() in guarantee_online_cpus() Will Deacon
2021-06-08 18:03   ` Will Deacon
2021-06-08 18:03 ` Will Deacon [this message]
2021-06-08 18:03   ` [PATCH v9 08/20] cpuset: Cleanup cpuset_cpus_allowed_fallback() use in select_fallback_rq() Will Deacon
2021-06-10 12:59   ` Valentin Schneider
2021-06-10 12:59     ` Valentin Schneider
2021-06-08 18:03 ` [PATCH v9 09/20] sched: Reject CPU affinity changes based on task_cpu_possible_mask() Will Deacon
2021-06-08 18:03   ` Will Deacon
2021-06-08 18:03 ` [PATCH v9 10/20] sched: Introduce task_struct::user_cpus_ptr to track requested affinity Will Deacon
2021-06-08 18:03   ` Will Deacon
2021-06-08 18:03 ` [PATCH v9 11/20] sched: Split the guts of sched_setaffinity() into a helper function Will Deacon
2021-06-08 18:03   ` Will Deacon
2021-06-08 18:03 ` [PATCH v9 12/20] sched: Allow task CPU affinity to be restricted on asymmetric systems Will Deacon
2021-06-08 18:03   ` Will Deacon
2021-06-10 13:00   ` Valentin Schneider
2021-06-10 13:00     ` Valentin Schneider
2021-06-08 18:03 ` [PATCH v9 13/20] sched: Introduce dl_task_check_affinity() to check proposed affinity Will Deacon
2021-06-08 18:03   ` Will Deacon
2021-06-08 18:03 ` [PATCH v9 14/20] arm64: Implement task_cpu_possible_mask() Will Deacon
2021-06-08 18:03   ` Will Deacon
2021-06-08 18:03 ` [PATCH v9 15/20] arm64: exec: Adjust affinity for compat tasks with mismatched 32-bit EL0 Will Deacon
2021-06-08 18:03   ` Will Deacon
2021-06-08 18:03 ` [PATCH v9 16/20] arm64: Prevent offlining first CPU with 32-bit EL0 on mismatched system Will Deacon
2021-06-08 18:03   ` Will Deacon
2021-06-08 18:03 ` [PATCH v9 17/20] arm64: Advertise CPUs capable of running 32-bit applications in sysfs Will Deacon
2021-06-08 18:03   ` Will Deacon
2021-06-08 18:03 ` [PATCH v9 18/20] arm64: Hook up cmdline parameter to allow mismatched 32-bit EL0 Will Deacon
2021-06-08 18:03   ` Will Deacon
2021-06-08 18:03 ` [PATCH v9 19/20] arm64: Remove logic to kill 32-bit tasks on 64-bit-only cores Will Deacon
2021-06-08 18:03   ` Will Deacon
2021-06-08 18:03 ` [PATCH v9 20/20] Documentation: arm64: describe asymmetric 32-bit support Will Deacon
2021-06-08 18:03   ` Will Deacon
2021-06-11 16:15 ` [PATCH v9 00/20] Add support for 32-bit tasks on asymmetric AArch32 systems Will Deacon
2021-06-11 16:15   ` Will Deacon

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