[PATCH v4 0/4] sched: Miscellaneous isolation related cleanups

[PATCH v4 0/4] sched: Miscellaneous isolation related cleanups

[Waiman Long]

 v4:
  - Make "isolcpus=nohz" equivalent to "nohz_full" as suggested by
    Federic.
  - Update the scheduler code to use HK_TYPE_KERNEL_NOISE.

 v3:
  - Fix incorrect housekeeping_nohz_full_setup() flags setting.

 v2:
  - Remove HK_TYPE_SCHED and related dead code
  - Change consolidated name from HK_TYPE_NOHZ_FULL to
    HK_TYPE_KERNEL_NOSISE as suggested by Frederic and update
    isolation.c as well.

This series contains a number of miscellaneous sched/isolation related
cleanups. Other than reducing the number of cpumasks in the housekeeping
structure, there should be no other functional change.

[v1] https://lore.kernel.org/lkml/20240818234520.90186-1-longman@redhat.com/
[v2] https://lore.kernel.org/lkml/20240904171441.1048072-1-longman@redhat.com/
[v3] https://lore.kernel.org/lkml/20240904183650.1053708-1-longman@redhat.com/

Waiman Long (4):
  sched/core: Remove HK_TYPE_SCHED
  sched/isolation: Make "isolcpus=nohz" equivalent to "nohz_full"
  sched/isolation: Consolidate housekeeping cpumasks that are always
    identical
  sched: Unify HK_TYPE_{TIMER|TICK|MISC} to HK_TYPE_KERNEL_NOISE

 .../admin-guide/kernel-parameters.txt         |  4 +++-
 include/linux/sched/isolation.h               | 21 +++++++++++-------
 kernel/sched/core.c                           | 12 +++++-----
 kernel/sched/fair.c                           | 19 +++-------------
 kernel/sched/isolation.c                      | 22 ++++++++-----------
 5 files changed, 34 insertions(+), 44 deletions(-)

-- 
2.43.5

[PATCH v4 1/4] sched/core: Remove HK_TYPE_SCHED

[Waiman Long]

The HK_TYPE_SCHED housekeeping type is defined but not set anywhere. So
any code that try to use HK_TYPE_SCHED are essentially dead code. So
remove HK_TYPE_SCHED and any code that use it.

Signed-off-by: Waiman Long <longman@redhat.com>
---
 include/linux/sched/isolation.h |  1 -
 kernel/sched/fair.c             | 14 --------------
 kernel/sched/isolation.c        |  1 -
 3 files changed, 16 deletions(-)

diff --git a/include/linux/sched/isolation.h b/include/linux/sched/isolation.h
index 2b461129d1fa..499d5e480882 100644
--- a/include/linux/sched/isolation.h
+++ b/include/linux/sched/isolation.h
@@ -10,7 +10,6 @@ enum hk_type {
 	HK_TYPE_TIMER,
 	HK_TYPE_RCU,
 	HK_TYPE_MISC,
-	HK_TYPE_SCHED,
 	HK_TYPE_TICK,
 	HK_TYPE_DOMAIN,
 	HK_TYPE_WQ,
diff --git a/kernel/sched/fair.c b/kernel/sched/fair.c
index b9784e13e6b6..f76690c15bfe 100644
--- a/kernel/sched/fair.c
+++ b/kernel/sched/fair.c
@@ -12202,9 +12202,6 @@ static inline int on_null_domain(struct rq *rq)
  * - When one of the busy CPUs notices that there may be an idle rebalancing
  *   needed, they will kick the idle load balancer, which then does idle
  *   load balancing for all the idle CPUs.
- *
- * - HK_TYPE_MISC CPUs are used for this task, because HK_TYPE_SCHED is not set
- *   anywhere yet.
  */
 static inline int find_new_ilb(void)
 {
@@ -12449,10 +12446,6 @@ void nohz_balance_enter_idle(int cpu)
 	if (!cpu_active(cpu))
 		return;
 
-	/* Spare idle load balancing on CPUs that don't want to be disturbed: */
-	if (!housekeeping_cpu(cpu, HK_TYPE_SCHED))
-		return;
-
 	/*
 	 * Can be set safely without rq->lock held
 	 * If a clear happens, it will have evaluated last additions because
@@ -12672,13 +12665,6 @@ static void nohz_newidle_balance(struct rq *this_rq)
 {
 	int this_cpu = this_rq->cpu;
 
-	/*
-	 * This CPU doesn't want to be disturbed by scheduler
-	 * housekeeping
-	 */
-	if (!housekeeping_cpu(this_cpu, HK_TYPE_SCHED))
-		return;
-
 	/* Will wake up very soon. No time for doing anything else*/
 	if (this_rq->avg_idle < sysctl_sched_migration_cost)
 		return;
diff --git a/kernel/sched/isolation.c b/kernel/sched/isolation.c
index 5891e715f00d..5345e11f3d44 100644
--- a/kernel/sched/isolation.c
+++ b/kernel/sched/isolation.c
@@ -12,7 +12,6 @@ enum hk_flags {
 	HK_FLAG_TIMER		= BIT(HK_TYPE_TIMER),
 	HK_FLAG_RCU		= BIT(HK_TYPE_RCU),
 	HK_FLAG_MISC		= BIT(HK_TYPE_MISC),
-	HK_FLAG_SCHED		= BIT(HK_TYPE_SCHED),
 	HK_FLAG_TICK		= BIT(HK_TYPE_TICK),
 	HK_FLAG_DOMAIN		= BIT(HK_TYPE_DOMAIN),
 	HK_FLAG_WQ		= BIT(HK_TYPE_WQ),
-- 
2.43.5

Re: [PATCH v4 1/4] sched/core: Remove HK_TYPE_SCHED

[Frederic Weisbecker]

Le Sat, Sep 21, 2024 at 03:07:17PM -0400, Waiman Long a écrit :
> The HK_TYPE_SCHED housekeeping type is defined but not set anywhere. So
> any code that try to use HK_TYPE_SCHED are essentially dead code. So
> remove HK_TYPE_SCHED and any code that use it.
> 
> Signed-off-by: Waiman Long <longman@redhat.com>

Acked-by: Frederic Weisbecker <frederic@kernel.org>

[PATCH v4 2/4] sched/isolation: Make "isolcpus=nohz" equivalent to "nohz_full"

[Waiman Long]

The "isolcpus=nohz" boot parameter and flag were used to disable tick
when running a single task.  Nowsdays, this "nohz" flag is seldomly used
as it is included as part of the "nohz_full" parameter.  Extend this
flag to cover other kernel noises disabled by the "nohz_full" parameter
to make them equivalent. This also eliminates the need to use both the
"isolcpus" and the "nohz_full" parameters to fully isolated a given
set of CPUs.

Suggested-by: Frederic Weisbecker <frederic@kernel.org>
Signed-off-by: Waiman Long <longman@redhat.com>
---
 Documentation/admin-guide/kernel-parameters.txt | 4 +++-
 kernel/sched/isolation.c                        | 6 +++++-
 2 files changed, 8 insertions(+), 2 deletions(-)

diff --git a/Documentation/admin-guide/kernel-parameters.txt b/Documentation/admin-guide/kernel-parameters.txt
index 8337d0fed311..4e664587943f 100644
--- a/Documentation/admin-guide/kernel-parameters.txt
+++ b/Documentation/admin-guide/kernel-parameters.txt
@@ -2424,7 +2424,9 @@
 			specified in the flag list (default: domain):
 
 			nohz
-			  Disable the tick when a single task runs.
+			  Disable the tick when a single task runs as well as
+			  disabling other kernel noises like having RCU callbacks
+			  offloaded. This is equivalent to the nohz_full parameter.
 
 			  A residual 1Hz tick is offloaded to workqueues, which you
 			  need to affine to housekeeping through the global
diff --git a/kernel/sched/isolation.c b/kernel/sched/isolation.c
index 5345e11f3d44..6a686322ce3c 100644
--- a/kernel/sched/isolation.c
+++ b/kernel/sched/isolation.c
@@ -209,9 +209,13 @@ static int __init housekeeping_isolcpus_setup(char *str)
 	int len;
 
 	while (isalpha(*str)) {
+		/*
+		 * isolcpus=nohz is equivalent to nohz_full.
+		 */
 		if (!strncmp(str, "nohz,", 5)) {
 			str += 5;
-			flags |= HK_FLAG_TICK;
+			flags |= HK_FLAG_TICK | HK_FLAG_WQ | HK_FLAG_TIMER |
+				 HK_FLAG_RCU | HK_FLAG_MISC | HK_FLAG_KTHREAD;
 			continue;
 		}
 
-- 
2.43.5

Re: [PATCH v4 2/4] sched/isolation: Make "isolcpus=nohz" equivalent to "nohz_full"

[Frederic Weisbecker]

Le Sat, Sep 21, 2024 at 03:07:18PM -0400, Waiman Long a écrit :
> The "isolcpus=nohz" boot parameter and flag were used to disable tick
> when running a single task.  Nowsdays, this "nohz" flag is seldomly used
> as it is included as part of the "nohz_full" parameter.  Extend this
> flag to cover other kernel noises disabled by the "nohz_full" parameter
> to make them equivalent. This also eliminates the need to use both the
> "isolcpus" and the "nohz_full" parameters to fully isolated a given
> set of CPUs.
> 
> Suggested-by: Frederic Weisbecker <frederic@kernel.org>
> Signed-off-by: Waiman Long <longman@redhat.com>

Acked-by: Frederic Weisbecker <frederic@kernel.org>

[PATCH v4 3/4] sched/isolation: Consolidate housekeeping cpumasks that are always identical

[Waiman Long]

The housekeeping cpumasks are only set by two boot commandline
parameters: "nohz_full" and "isolcpus". When there is more than one of
"nohz_full" or "isolcpus", the extra ones must have the same CPU list
or the setup will fail partially.

The HK_TYPE_DOMAIN and HK_TYPE_MANAGED_IRQ types are settable by
"isolcpus" only and their settings can be independent of the other
types. The other housekeeping types are all set by "nohz_full" or
"isolcpus=nohz" without a way to set them individually. So they all
have identical cpumasks.

There is actually no point in having different cpumasks for these
"nohz_full" only housekeeping types. Consolidate these types to use the
same cpumask by aliasing them to the same value. If there is a need to
set any of them independently in the future, we can break them out to
their own cpumasks again.

With this change, the number of cpumasks in the housekeeping structure
drops from 9 to 3. Other than that, there should be no other functional
change.

Signed-off-by: Waiman Long <longman@redhat.com>
---
 include/linux/sched/isolation.h | 20 +++++++++++++-------
 kernel/sched/isolation.c        | 19 ++++++-------------
 2 files changed, 19 insertions(+), 20 deletions(-)

diff --git a/include/linux/sched/isolation.h b/include/linux/sched/isolation.h
index 499d5e480882..d8501f4709b5 100644
--- a/include/linux/sched/isolation.h
+++ b/include/linux/sched/isolation.h
@@ -7,15 +7,21 @@
 #include <linux/tick.h>
 
 enum hk_type {
-	HK_TYPE_TIMER,
-	HK_TYPE_RCU,
-	HK_TYPE_MISC,
-	HK_TYPE_TICK,
 	HK_TYPE_DOMAIN,
-	HK_TYPE_WQ,
 	HK_TYPE_MANAGED_IRQ,
-	HK_TYPE_KTHREAD,
-	HK_TYPE_MAX
+	HK_TYPE_KERNEL_NOISE,
+	HK_TYPE_MAX,
+
+	/*
+	 * The following housekeeping types are only set by the nohz_full
+	 * boot commandline option. So they can share the same value.
+	 */
+	HK_TYPE_TICK    = HK_TYPE_KERNEL_NOISE,
+	HK_TYPE_TIMER   = HK_TYPE_KERNEL_NOISE,
+	HK_TYPE_RCU     = HK_TYPE_KERNEL_NOISE,
+	HK_TYPE_MISC    = HK_TYPE_KERNEL_NOISE,
+	HK_TYPE_WQ      = HK_TYPE_KERNEL_NOISE,
+	HK_TYPE_KTHREAD = HK_TYPE_KERNEL_NOISE
 };
 
 #ifdef CONFIG_CPU_ISOLATION
diff --git a/kernel/sched/isolation.c b/kernel/sched/isolation.c
index 6a686322ce3c..81bc8b329ef1 100644
--- a/kernel/sched/isolation.c
+++ b/kernel/sched/isolation.c
@@ -9,14 +9,9 @@
  */
 
 enum hk_flags {
-	HK_FLAG_TIMER		= BIT(HK_TYPE_TIMER),
-	HK_FLAG_RCU		= BIT(HK_TYPE_RCU),
-	HK_FLAG_MISC		= BIT(HK_TYPE_MISC),
-	HK_FLAG_TICK		= BIT(HK_TYPE_TICK),
 	HK_FLAG_DOMAIN		= BIT(HK_TYPE_DOMAIN),
-	HK_FLAG_WQ		= BIT(HK_TYPE_WQ),
 	HK_FLAG_MANAGED_IRQ	= BIT(HK_TYPE_MANAGED_IRQ),
-	HK_FLAG_KTHREAD		= BIT(HK_TYPE_KTHREAD),
+	HK_FLAG_KERNEL_NOISE	= BIT(HK_TYPE_KERNEL_NOISE),
 };
 
 DEFINE_STATIC_KEY_FALSE(housekeeping_overridden);
@@ -96,7 +91,7 @@ void __init housekeeping_init(void)
 
 	static_branch_enable(&housekeeping_overridden);
 
-	if (housekeeping.flags & HK_FLAG_TICK)
+	if (housekeeping.flags & HK_FLAG_KERNEL_NOISE)
 		sched_tick_offload_init();
 
 	for_each_set_bit(type, &housekeeping.flags, HK_TYPE_MAX) {
@@ -120,7 +115,7 @@ static int __init housekeeping_setup(char *str, unsigned long flags)
 	unsigned int first_cpu;
 	int err = 0;
 
-	if ((flags & HK_FLAG_TICK) && !(housekeeping.flags & HK_FLAG_TICK)) {
+	if ((flags & HK_FLAG_KERNEL_NOISE) && !(housekeeping.flags & HK_FLAG_KERNEL_NOISE)) {
 		if (!IS_ENABLED(CONFIG_NO_HZ_FULL)) {
 			pr_warn("Housekeeping: nohz unsupported."
 				" Build with CONFIG_NO_HZ_FULL\n");
@@ -176,7 +171,7 @@ static int __init housekeeping_setup(char *str, unsigned long flags)
 			housekeeping_setup_type(type, housekeeping_staging);
 	}
 
-	if ((flags & HK_FLAG_TICK) && !(housekeeping.flags & HK_FLAG_TICK))
+	if ((flags & HK_FLAG_KERNEL_NOISE) && !(housekeeping.flags & HK_FLAG_KERNEL_NOISE))
 		tick_nohz_full_setup(non_housekeeping_mask);
 
 	housekeeping.flags |= flags;
@@ -194,8 +189,7 @@ static int __init housekeeping_nohz_full_setup(char *str)
 {
 	unsigned long flags;
 
-	flags = HK_FLAG_TICK | HK_FLAG_WQ | HK_FLAG_TIMER | HK_FLAG_RCU |
-		HK_FLAG_MISC | HK_FLAG_KTHREAD;
+	flags = HK_FLAG_KERNEL_NOISE;
 
 	return housekeeping_setup(str, flags);
 }
@@ -214,8 +208,7 @@ static int __init housekeeping_isolcpus_setup(char *str)
 		 */
 		if (!strncmp(str, "nohz,", 5)) {
 			str += 5;
-			flags |= HK_FLAG_TICK | HK_FLAG_WQ | HK_FLAG_TIMER |
-				 HK_FLAG_RCU | HK_FLAG_MISC | HK_FLAG_KTHREAD;
+			flags |= HK_FLAG_KERNEL_NOISE;
 			continue;
 		}
 
-- 
2.43.5

Re: [PATCH v4 3/4] sched/isolation: Consolidate housekeeping cpumasks that are always identical

[Frederic Weisbecker]

Le Sat, Sep 21, 2024 at 03:07:19PM -0400, Waiman Long a écrit :
> The housekeeping cpumasks are only set by two boot commandline
> parameters: "nohz_full" and "isolcpus". When there is more than one of
> "nohz_full" or "isolcpus", the extra ones must have the same CPU list
> or the setup will fail partially.
> 
> The HK_TYPE_DOMAIN and HK_TYPE_MANAGED_IRQ types are settable by
> "isolcpus" only and their settings can be independent of the other
> types. The other housekeeping types are all set by "nohz_full" or
> "isolcpus=nohz" without a way to set them individually. So they all
> have identical cpumasks.
> 
> There is actually no point in having different cpumasks for these
> "nohz_full" only housekeeping types. Consolidate these types to use the
> same cpumask by aliasing them to the same value. If there is a need to
> set any of them independently in the future, we can break them out to
> their own cpumasks again.
> 
> With this change, the number of cpumasks in the housekeeping structure
> drops from 9 to 3. Other than that, there should be no other functional
> change.
> 
> Signed-off-by: Waiman Long <longman@redhat.com>

Acked-by: Frederic Weisbecker <frederic@kernel.org>

[PATCH v4 4/4] sched: Unify HK_TYPE_{TIMER|TICK|MISC} to HK_TYPE_KERNEL_NOISE

[Waiman Long]

As all the non-domain and non-managed_irq housekeeping types have been
unified to HK_TYPE_KERNEL_NOISE, replace all these references in the
scheduler to use HK_TYPE_KERNEL_NOISE.

Signed-off-by: Waiman Long <longman@redhat.com>
---
 kernel/sched/core.c | 12 ++++++------
 kernel/sched/fair.c |  5 +++--
 2 files changed, 9 insertions(+), 8 deletions(-)

diff --git a/kernel/sched/core.c b/kernel/sched/core.c
index a7af49b3a337..3412d0046d08 100644
--- a/kernel/sched/core.c
+++ b/kernel/sched/core.c
@@ -1114,13 +1114,13 @@ int get_nohz_timer_target(void)
 	struct sched_domain *sd;
 	const struct cpumask *hk_mask;
 
-	if (housekeeping_cpu(cpu, HK_TYPE_TIMER)) {
+	if (housekeeping_cpu(cpu, HK_TYPE_KERNEL_NOISE)) {
 		if (!idle_cpu(cpu))
 			return cpu;
 		default_cpu = cpu;
 	}
 
-	hk_mask = housekeeping_cpumask(HK_TYPE_TIMER);
+	hk_mask = housekeeping_cpumask(HK_TYPE_KERNEL_NOISE);
 
 	guard(rcu)();
 
@@ -1135,7 +1135,7 @@ int get_nohz_timer_target(void)
 	}
 
 	if (default_cpu == -1)
-		default_cpu = housekeeping_any_cpu(HK_TYPE_TIMER);
+		default_cpu = housekeeping_any_cpu(HK_TYPE_KERNEL_NOISE);
 
 	return default_cpu;
 }
@@ -5526,7 +5526,7 @@ void sched_tick(void)
 	unsigned long hw_pressure;
 	u64 resched_latency;
 
-	if (housekeeping_cpu(cpu, HK_TYPE_TICK))
+	if (housekeeping_cpu(cpu, HK_TYPE_KERNEL_NOISE))
 		arch_scale_freq_tick();
 
 	sched_clock_tick();
@@ -5652,7 +5652,7 @@ static void sched_tick_start(int cpu)
 	int os;
 	struct tick_work *twork;
 
-	if (housekeeping_cpu(cpu, HK_TYPE_TICK))
+	if (housekeeping_cpu(cpu, HK_TYPE_KERNEL_NOISE))
 		return;
 
 	WARN_ON_ONCE(!tick_work_cpu);
@@ -5673,7 +5673,7 @@ static void sched_tick_stop(int cpu)
 	struct tick_work *twork;
 	int os;
 
-	if (housekeeping_cpu(cpu, HK_TYPE_TICK))
+	if (housekeeping_cpu(cpu, HK_TYPE_KERNEL_NOISE))
 		return;
 
 	WARN_ON_ONCE(!tick_work_cpu);
diff --git a/kernel/sched/fair.c b/kernel/sched/fair.c
index f76690c15bfe..08a3d024faf9 100644
--- a/kernel/sched/fair.c
+++ b/kernel/sched/fair.c
@@ -12208,7 +12208,7 @@ static inline int find_new_ilb(void)
 	const struct cpumask *hk_mask;
 	int ilb_cpu;
 
-	hk_mask = housekeeping_cpumask(HK_TYPE_MISC);
+	hk_mask = housekeeping_cpumask(HK_TYPE_KERNEL_NOISE);
 
 	for_each_cpu_and(ilb_cpu, nohz.idle_cpus_mask, hk_mask) {
 
@@ -12226,7 +12226,8 @@ static inline int find_new_ilb(void)
  * Kick a CPU to do the NOHZ balancing, if it is time for it, via a cross-CPU
  * SMP function call (IPI).
  *
- * We pick the first idle CPU in the HK_TYPE_MISC housekeeping set (if there is one).
+ * We pick the first idle CPU in the HK_TYPE_KERNEL_NOISE housekeeping set
+ * (if there is one).
  */
 static void kick_ilb(unsigned int flags)
 {
-- 
2.43.5

Re: [PATCH v4 4/4] sched: Unify HK_TYPE_{TIMER|TICK|MISC} to HK_TYPE_KERNEL_NOISE

[Frederic Weisbecker]

Le Sat, Sep 21, 2024 at 03:07:20PM -0400, Waiman Long a écrit :
> As all the non-domain and non-managed_irq housekeeping types have been
> unified to HK_TYPE_KERNEL_NOISE, replace all these references in the
> scheduler to use HK_TYPE_KERNEL_NOISE.
> 
> Signed-off-by: Waiman Long <longman@redhat.com>

Acked-by: Frederic Weisbecker <frederic@kernel.org>

Re: [PATCH v4 0/4] sched: Miscellaneous isolation related cleanups

[Waiman Long]

On 9/21/24 3:07 PM, Waiman Long wrote:
>   v4:
>    - Make "isolcpus=nohz" equivalent to "nohz_full" as suggested by
>      Federic.
>    - Update the scheduler code to use HK_TYPE_KERNEL_NOISE.
>
>   v3:
>    - Fix incorrect housekeeping_nohz_full_setup() flags setting.
>
>   v2:
>    - Remove HK_TYPE_SCHED and related dead code
>    - Change consolidated name from HK_TYPE_NOHZ_FULL to
>      HK_TYPE_KERNEL_NOSISE as suggested by Frederic and update
>      isolation.c as well.
>
> This series contains a number of miscellaneous sched/isolation related
> cleanups. Other than reducing the number of cpumasks in the housekeeping
> structure, there should be no other functional change.
>
> [v1] https://lore.kernel.org/lkml/20240818234520.90186-1-longman@redhat.com/
> [v2] https://lore.kernel.org/lkml/20240904171441.1048072-1-longman@redhat.com/
> [v3] https://lore.kernel.org/lkml/20240904183650.1053708-1-longman@redhat.com/
>
> Waiman Long (4):
>    sched/core: Remove HK_TYPE_SCHED
>    sched/isolation: Make "isolcpus=nohz" equivalent to "nohz_full"
>    sched/isolation: Consolidate housekeeping cpumasks that are always
>      identical
>    sched: Unify HK_TYPE_{TIMER|TICK|MISC} to HK_TYPE_KERNEL_NOISE
>
>   .../admin-guide/kernel-parameters.txt         |  4 +++-
>   include/linux/sched/isolation.h               | 21 +++++++++++-------
>   kernel/sched/core.c                           | 12 +++++-----
>   kernel/sched/fair.c                           | 19 +++-------------
>   kernel/sched/isolation.c                      | 22 ++++++++-----------
>   5 files changed, 34 insertions(+), 44 deletions(-)
>
Peter, are you fine with the changes in this series? I got the acks from 
Frederic, but I haven't receive any comments after that.

Thanks,
Longman

[RESEND PATCH v4 0/4] sched: Miscellaneous isolation related cleanups

[Waiman Long]

 v4:
  - Make "isolcpus=nohz" equivalent to "nohz_full" as suggested by
    Federic.
  - Update the scheduler code to use HK_TYPE_KERNEL_NOISE.

 v3:
  - Fix incorrect housekeeping_nohz_full_setup() flags setting.

 v2:
  - Remove HK_TYPE_SCHED and related dead code
  - Change consolidated name from HK_TYPE_NOHZ_FULL to
    HK_TYPE_KERNEL_NOSISE as suggested by Frederic and update
    isolation.c as well.

This series contains a number of miscellaneous sched/isolation related
cleanups. Other than reducing the number of cpumasks in the housekeeping
structure, there should be no other functional change.

[v1] https://lore.kernel.org/lkml/20240818234520.90186-1-longman@redhat.com/
[v2] https://lore.kernel.org/lkml/20240904171441.1048072-1-longman@redhat.com/
[v3] https://lore.kernel.org/lkml/20240904183650.1053708-1-longman@redhat.com/

Waiman Long (4):
  sched/core: Remove HK_TYPE_SCHED
  sched/isolation: Make "isolcpus=nohz" equivalent to "nohz_full"
  sched/isolation: Consolidate housekeeping cpumasks that are always
    identical
  sched: Unify HK_TYPE_{TIMER|TICK|MISC} to HK_TYPE_KERNEL_NOISE

 .../admin-guide/kernel-parameters.txt         |  4 +++-
 include/linux/sched/isolation.h               | 21 +++++++++++-------
 kernel/sched/core.c                           | 12 +++++-----
 kernel/sched/fair.c                           | 19 +++-------------
 kernel/sched/isolation.c                      | 22 ++++++++-----------
 5 files changed, 34 insertions(+), 44 deletions(-)

-- 
2.43.5

[RESEND PATCH v4 1/4] sched/core: Remove HK_TYPE_SCHED

[Waiman Long]

The HK_TYPE_SCHED housekeeping type is defined but not set anywhere. So
any code that try to use HK_TYPE_SCHED are essentially dead code. So
remove HK_TYPE_SCHED and any code that use it.

Signed-off-by: Waiman Long <longman@redhat.com>
Acked-by: Frederic Weisbecker <frederic@kernel.org>
---
 include/linux/sched/isolation.h |  1 -
 kernel/sched/fair.c             | 14 --------------
 kernel/sched/isolation.c        |  1 -
 3 files changed, 16 deletions(-)

diff --git a/include/linux/sched/isolation.h b/include/linux/sched/isolation.h
index 2b461129d1fa..499d5e480882 100644
--- a/include/linux/sched/isolation.h
+++ b/include/linux/sched/isolation.h
@@ -10,7 +10,6 @@ enum hk_type {
 	HK_TYPE_TIMER,
 	HK_TYPE_RCU,
 	HK_TYPE_MISC,
-	HK_TYPE_SCHED,
 	HK_TYPE_TICK,
 	HK_TYPE_DOMAIN,
 	HK_TYPE_WQ,
diff --git a/kernel/sched/fair.c b/kernel/sched/fair.c
index b9784e13e6b6..f76690c15bfe 100644
--- a/kernel/sched/fair.c
+++ b/kernel/sched/fair.c
@@ -12202,9 +12202,6 @@ static inline int on_null_domain(struct rq *rq)
  * - When one of the busy CPUs notices that there may be an idle rebalancing
  *   needed, they will kick the idle load balancer, which then does idle
  *   load balancing for all the idle CPUs.
- *
- * - HK_TYPE_MISC CPUs are used for this task, because HK_TYPE_SCHED is not set
- *   anywhere yet.
  */
 static inline int find_new_ilb(void)
 {
@@ -12449,10 +12446,6 @@ void nohz_balance_enter_idle(int cpu)
 	if (!cpu_active(cpu))
 		return;
 
-	/* Spare idle load balancing on CPUs that don't want to be disturbed: */
-	if (!housekeeping_cpu(cpu, HK_TYPE_SCHED))
-		return;
-
 	/*
 	 * Can be set safely without rq->lock held
 	 * If a clear happens, it will have evaluated last additions because
@@ -12672,13 +12665,6 @@ static void nohz_newidle_balance(struct rq *this_rq)
 {
 	int this_cpu = this_rq->cpu;
 
-	/*
-	 * This CPU doesn't want to be disturbed by scheduler
-	 * housekeeping
-	 */
-	if (!housekeeping_cpu(this_cpu, HK_TYPE_SCHED))
-		return;
-
 	/* Will wake up very soon. No time for doing anything else*/
 	if (this_rq->avg_idle < sysctl_sched_migration_cost)
 		return;
diff --git a/kernel/sched/isolation.c b/kernel/sched/isolation.c
index 5891e715f00d..5345e11f3d44 100644
--- a/kernel/sched/isolation.c
+++ b/kernel/sched/isolation.c
@@ -12,7 +12,6 @@ enum hk_flags {
 	HK_FLAG_TIMER		= BIT(HK_TYPE_TIMER),
 	HK_FLAG_RCU		= BIT(HK_TYPE_RCU),
 	HK_FLAG_MISC		= BIT(HK_TYPE_MISC),
-	HK_FLAG_SCHED		= BIT(HK_TYPE_SCHED),
 	HK_FLAG_TICK		= BIT(HK_TYPE_TICK),
 	HK_FLAG_DOMAIN		= BIT(HK_TYPE_DOMAIN),
 	HK_FLAG_WQ		= BIT(HK_TYPE_WQ),
-- 
2.43.5

[tip: sched/core] sched/core: Remove HK_TYPE_SCHED

[tip-bot2 for Waiman Long]

The following commit has been merged into the sched/core branch of tip:

Commit-ID:     ae5c677729e99b8cb3e6252aaa9b72a92985d203
Gitweb:        https://git.kernel.org/tip/ae5c677729e99b8cb3e6252aaa9b72a92985d203
Author:        Waiman Long <longman@redhat.com>
AuthorDate:    Wed, 30 Oct 2024 13:52:50 -04:00
Committer:     Peter Zijlstra <peterz@infradead.org>
CommitterDate: Mon, 02 Dec 2024 12:24:27 +01:00

sched/core: Remove HK_TYPE_SCHED

The HK_TYPE_SCHED housekeeping type is defined but not set anywhere. So
any code that try to use HK_TYPE_SCHED are essentially dead code. So
remove HK_TYPE_SCHED and any code that use it.

Signed-off-by: Waiman Long <longman@redhat.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Acked-by: Frederic Weisbecker <frederic@kernel.org>
Link: https://lore.kernel.org/r/20241030175253.125248-2-longman@redhat.com
---
 include/linux/sched/isolation.h |  1 -
 kernel/sched/fair.c             | 14 --------------
 kernel/sched/isolation.c        |  1 -
 3 files changed, 16 deletions(-)

diff --git a/include/linux/sched/isolation.h b/include/linux/sched/isolation.h
index 2b46112..499d5e4 100644
--- a/include/linux/sched/isolation.h
+++ b/include/linux/sched/isolation.h
@@ -10,7 +10,6 @@ enum hk_type {
 	HK_TYPE_TIMER,
 	HK_TYPE_RCU,
 	HK_TYPE_MISC,
-	HK_TYPE_SCHED,
 	HK_TYPE_TICK,
 	HK_TYPE_DOMAIN,
 	HK_TYPE_WQ,
diff --git a/kernel/sched/fair.c b/kernel/sched/fair.c
index 4283c81..ef30226 100644
--- a/kernel/sched/fair.c
+++ b/kernel/sched/fair.c
@@ -12197,9 +12197,6 @@ static inline int on_null_domain(struct rq *rq)
  * - When one of the busy CPUs notices that there may be an idle rebalancing
  *   needed, they will kick the idle load balancer, which then does idle
  *   load balancing for all the idle CPUs.
- *
- * - HK_TYPE_MISC CPUs are used for this task, because HK_TYPE_SCHED is not set
- *   anywhere yet.
  */
 static inline int find_new_ilb(void)
 {
@@ -12444,10 +12441,6 @@ void nohz_balance_enter_idle(int cpu)
 	if (!cpu_active(cpu))
 		return;
 
-	/* Spare idle load balancing on CPUs that don't want to be disturbed: */
-	if (!housekeeping_cpu(cpu, HK_TYPE_SCHED))
-		return;
-
 	/*
 	 * Can be set safely without rq->lock held
 	 * If a clear happens, it will have evaluated last additions because
@@ -12667,13 +12660,6 @@ static void nohz_newidle_balance(struct rq *this_rq)
 {
 	int this_cpu = this_rq->cpu;
 
-	/*
-	 * This CPU doesn't want to be disturbed by scheduler
-	 * housekeeping
-	 */
-	if (!housekeeping_cpu(this_cpu, HK_TYPE_SCHED))
-		return;
-
 	/* Will wake up very soon. No time for doing anything else*/
 	if (this_rq->avg_idle < sysctl_sched_migration_cost)
 		return;
diff --git a/kernel/sched/isolation.c b/kernel/sched/isolation.c
index 5891e71..5345e11 100644
--- a/kernel/sched/isolation.c
+++ b/kernel/sched/isolation.c
@@ -12,7 +12,6 @@ enum hk_flags {
 	HK_FLAG_TIMER		= BIT(HK_TYPE_TIMER),
 	HK_FLAG_RCU		= BIT(HK_TYPE_RCU),
 	HK_FLAG_MISC		= BIT(HK_TYPE_MISC),
-	HK_FLAG_SCHED		= BIT(HK_TYPE_SCHED),
 	HK_FLAG_TICK		= BIT(HK_TYPE_TICK),
 	HK_FLAG_DOMAIN		= BIT(HK_TYPE_DOMAIN),
 	HK_FLAG_WQ		= BIT(HK_TYPE_WQ),

[RESEND PATCH v4 2/4] sched/isolation: Make "isolcpus=nohz" equivalent to "nohz_full"

[Waiman Long]

The "isolcpus=nohz" boot parameter and flag were used to disable tick
when running a single task.  Nowsdays, this "nohz" flag is seldomly used
as it is included as part of the "nohz_full" parameter.  Extend this
flag to cover other kernel noises disabled by the "nohz_full" parameter
to make them equivalent. This also eliminates the need to use both the
"isolcpus" and the "nohz_full" parameters to fully isolated a given
set of CPUs.

Suggested-by: Frederic Weisbecker <frederic@kernel.org>
Signed-off-by: Waiman Long <longman@redhat.com>
Acked-by: Frederic Weisbecker <frederic@kernel.org>
---
 Documentation/admin-guide/kernel-parameters.txt | 4 +++-
 kernel/sched/isolation.c                        | 6 +++++-
 2 files changed, 8 insertions(+), 2 deletions(-)

diff --git a/Documentation/admin-guide/kernel-parameters.txt b/Documentation/admin-guide/kernel-parameters.txt
index 8337d0fed311..4e664587943f 100644
--- a/Documentation/admin-guide/kernel-parameters.txt
+++ b/Documentation/admin-guide/kernel-parameters.txt
@@ -2424,7 +2424,9 @@
 			specified in the flag list (default: domain):
 
 			nohz
-			  Disable the tick when a single task runs.
+			  Disable the tick when a single task runs as well as
+			  disabling other kernel noises like having RCU callbacks
+			  offloaded. This is equivalent to the nohz_full parameter.
 
 			  A residual 1Hz tick is offloaded to workqueues, which you
 			  need to affine to housekeeping through the global
diff --git a/kernel/sched/isolation.c b/kernel/sched/isolation.c
index 5345e11f3d44..6a686322ce3c 100644
--- a/kernel/sched/isolation.c
+++ b/kernel/sched/isolation.c
@@ -209,9 +209,13 @@ static int __init housekeeping_isolcpus_setup(char *str)
 	int len;
 
 	while (isalpha(*str)) {
+		/*
+		 * isolcpus=nohz is equivalent to nohz_full.
+		 */
 		if (!strncmp(str, "nohz,", 5)) {
 			str += 5;
-			flags |= HK_FLAG_TICK;
+			flags |= HK_FLAG_TICK | HK_FLAG_WQ | HK_FLAG_TIMER |
+				 HK_FLAG_RCU | HK_FLAG_MISC | HK_FLAG_KTHREAD;
 			continue;
 		}
 
-- 
2.43.5

[tip: sched/core] sched/isolation: Make "isolcpus=nohz" equivalent to "nohz_full"

[tip-bot2 for Waiman Long]

The following commit has been merged into the sched/core branch of tip:

Commit-ID:     1174b9344bc7e7989439cad207fcd94eaab028db
Gitweb:        https://git.kernel.org/tip/1174b9344bc7e7989439cad207fcd94eaab028db
Author:        Waiman Long <longman@redhat.com>
AuthorDate:    Wed, 30 Oct 2024 13:52:51 -04:00
Committer:     Peter Zijlstra <peterz@infradead.org>
CommitterDate: Mon, 02 Dec 2024 12:24:28 +01:00

sched/isolation: Make "isolcpus=nohz" equivalent to "nohz_full"

The "isolcpus=nohz" boot parameter and flag were used to disable tick
when running a single task.  Nowsdays, this "nohz" flag is seldomly used
as it is included as part of the "nohz_full" parameter.  Extend this
flag to cover other kernel noises disabled by the "nohz_full" parameter
to make them equivalent. This also eliminates the need to use both the
"isolcpus" and the "nohz_full" parameters to fully isolated a given
set of CPUs.

Suggested-by: Frederic Weisbecker <frederic@kernel.org>
Signed-off-by: Waiman Long <longman@redhat.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Acked-by: Frederic Weisbecker <frederic@kernel.org>
Link: https://lore.kernel.org/r/20241030175253.125248-3-longman@redhat.com
---
 Documentation/admin-guide/kernel-parameters.txt | 4 +++-
 kernel/sched/isolation.c                        | 6 +++++-
 2 files changed, 8 insertions(+), 2 deletions(-)

diff --git a/Documentation/admin-guide/kernel-parameters.txt b/Documentation/admin-guide/kernel-parameters.txt
index 3872bc6..3fa0b4e 100644
--- a/Documentation/admin-guide/kernel-parameters.txt
+++ b/Documentation/admin-guide/kernel-parameters.txt
@@ -2432,7 +2432,9 @@
 			specified in the flag list (default: domain):
 
 			nohz
-			  Disable the tick when a single task runs.
+			  Disable the tick when a single task runs as well as
+			  disabling other kernel noises like having RCU callbacks
+			  offloaded. This is equivalent to the nohz_full parameter.
 
 			  A residual 1Hz tick is offloaded to workqueues, which you
 			  need to affine to housekeeping through the global
diff --git a/kernel/sched/isolation.c b/kernel/sched/isolation.c
index 5345e11..6a68632 100644
--- a/kernel/sched/isolation.c
+++ b/kernel/sched/isolation.c
@@ -209,9 +209,13 @@ static int __init housekeeping_isolcpus_setup(char *str)
 	int len;
 
 	while (isalpha(*str)) {
+		/*
+		 * isolcpus=nohz is equivalent to nohz_full.
+		 */
 		if (!strncmp(str, "nohz,", 5)) {
 			str += 5;
-			flags |= HK_FLAG_TICK;
+			flags |= HK_FLAG_TICK | HK_FLAG_WQ | HK_FLAG_TIMER |
+				 HK_FLAG_RCU | HK_FLAG_MISC | HK_FLAG_KTHREAD;
 			continue;
 		}
 

[RESEND PATCH v4 3/4] sched/isolation: Consolidate housekeeping cpumasks that are always identical

[Waiman Long]

The housekeeping cpumasks are only set by two boot commandline
parameters: "nohz_full" and "isolcpus". When there is more than one of
"nohz_full" or "isolcpus", the extra ones must have the same CPU list
or the setup will fail partially.

The HK_TYPE_DOMAIN and HK_TYPE_MANAGED_IRQ types are settable by
"isolcpus" only and their settings can be independent of the other
types. The other housekeeping types are all set by "nohz_full" or
"isolcpus=nohz" without a way to set them individually. So they all
have identical cpumasks.

There is actually no point in having different cpumasks for these
"nohz_full" only housekeeping types. Consolidate these types to use the
same cpumask by aliasing them to the same value. If there is a need to
set any of them independently in the future, we can break them out to
their own cpumasks again.

With this change, the number of cpumasks in the housekeeping structure
drops from 9 to 3. Other than that, there should be no other functional
change.

Signed-off-by: Waiman Long <longman@redhat.com>
Acked-by: Frederic Weisbecker <frederic@kernel.org>
---
 include/linux/sched/isolation.h | 20 +++++++++++++-------
 kernel/sched/isolation.c        | 19 ++++++-------------
 2 files changed, 19 insertions(+), 20 deletions(-)

diff --git a/include/linux/sched/isolation.h b/include/linux/sched/isolation.h
index 499d5e480882..d8501f4709b5 100644
--- a/include/linux/sched/isolation.h
+++ b/include/linux/sched/isolation.h
@@ -7,15 +7,21 @@
 #include <linux/tick.h>
 
 enum hk_type {
-	HK_TYPE_TIMER,
-	HK_TYPE_RCU,
-	HK_TYPE_MISC,
-	HK_TYPE_TICK,
 	HK_TYPE_DOMAIN,
-	HK_TYPE_WQ,
 	HK_TYPE_MANAGED_IRQ,
-	HK_TYPE_KTHREAD,
-	HK_TYPE_MAX
+	HK_TYPE_KERNEL_NOISE,
+	HK_TYPE_MAX,
+
+	/*
+	 * The following housekeeping types are only set by the nohz_full
+	 * boot commandline option. So they can share the same value.
+	 */
+	HK_TYPE_TICK    = HK_TYPE_KERNEL_NOISE,
+	HK_TYPE_TIMER   = HK_TYPE_KERNEL_NOISE,
+	HK_TYPE_RCU     = HK_TYPE_KERNEL_NOISE,
+	HK_TYPE_MISC    = HK_TYPE_KERNEL_NOISE,
+	HK_TYPE_WQ      = HK_TYPE_KERNEL_NOISE,
+	HK_TYPE_KTHREAD = HK_TYPE_KERNEL_NOISE
 };
 
 #ifdef CONFIG_CPU_ISOLATION
diff --git a/kernel/sched/isolation.c b/kernel/sched/isolation.c
index 6a686322ce3c..81bc8b329ef1 100644
--- a/kernel/sched/isolation.c
+++ b/kernel/sched/isolation.c
@@ -9,14 +9,9 @@
  */
 
 enum hk_flags {
-	HK_FLAG_TIMER		= BIT(HK_TYPE_TIMER),
-	HK_FLAG_RCU		= BIT(HK_TYPE_RCU),
-	HK_FLAG_MISC		= BIT(HK_TYPE_MISC),
-	HK_FLAG_TICK		= BIT(HK_TYPE_TICK),
 	HK_FLAG_DOMAIN		= BIT(HK_TYPE_DOMAIN),
-	HK_FLAG_WQ		= BIT(HK_TYPE_WQ),
 	HK_FLAG_MANAGED_IRQ	= BIT(HK_TYPE_MANAGED_IRQ),
-	HK_FLAG_KTHREAD		= BIT(HK_TYPE_KTHREAD),
+	HK_FLAG_KERNEL_NOISE	= BIT(HK_TYPE_KERNEL_NOISE),
 };
 
 DEFINE_STATIC_KEY_FALSE(housekeeping_overridden);
@@ -96,7 +91,7 @@ void __init housekeeping_init(void)
 
 	static_branch_enable(&housekeeping_overridden);
 
-	if (housekeeping.flags & HK_FLAG_TICK)
+	if (housekeeping.flags & HK_FLAG_KERNEL_NOISE)
 		sched_tick_offload_init();
 
 	for_each_set_bit(type, &housekeeping.flags, HK_TYPE_MAX) {
@@ -120,7 +115,7 @@ static int __init housekeeping_setup(char *str, unsigned long flags)
 	unsigned int first_cpu;
 	int err = 0;
 
-	if ((flags & HK_FLAG_TICK) && !(housekeeping.flags & HK_FLAG_TICK)) {
+	if ((flags & HK_FLAG_KERNEL_NOISE) && !(housekeeping.flags & HK_FLAG_KERNEL_NOISE)) {
 		if (!IS_ENABLED(CONFIG_NO_HZ_FULL)) {
 			pr_warn("Housekeeping: nohz unsupported."
 				" Build with CONFIG_NO_HZ_FULL\n");
@@ -176,7 +171,7 @@ static int __init housekeeping_setup(char *str, unsigned long flags)
 			housekeeping_setup_type(type, housekeeping_staging);
 	}
 
-	if ((flags & HK_FLAG_TICK) && !(housekeeping.flags & HK_FLAG_TICK))
+	if ((flags & HK_FLAG_KERNEL_NOISE) && !(housekeeping.flags & HK_FLAG_KERNEL_NOISE))
 		tick_nohz_full_setup(non_housekeeping_mask);
 
 	housekeeping.flags |= flags;
@@ -194,8 +189,7 @@ static int __init housekeeping_nohz_full_setup(char *str)
 {
 	unsigned long flags;
 
-	flags = HK_FLAG_TICK | HK_FLAG_WQ | HK_FLAG_TIMER | HK_FLAG_RCU |
-		HK_FLAG_MISC | HK_FLAG_KTHREAD;
+	flags = HK_FLAG_KERNEL_NOISE;
 
 	return housekeeping_setup(str, flags);
 }
@@ -214,8 +208,7 @@ static int __init housekeeping_isolcpus_setup(char *str)
 		 */
 		if (!strncmp(str, "nohz,", 5)) {
 			str += 5;
-			flags |= HK_FLAG_TICK | HK_FLAG_WQ | HK_FLAG_TIMER |
-				 HK_FLAG_RCU | HK_FLAG_MISC | HK_FLAG_KTHREAD;
+			flags |= HK_FLAG_KERNEL_NOISE;
 			continue;
 		}
 
-- 
2.43.5

[tip: sched/core] sched/isolation: Consolidate housekeeping cpumasks that are always identical

[tip-bot2 for Waiman Long]

The following commit has been merged into the sched/core branch of tip:

Commit-ID:     6010d245ddc9f463bbf0311ac49073a78f444755
Gitweb:        https://git.kernel.org/tip/6010d245ddc9f463bbf0311ac49073a78f444755
Author:        Waiman Long <longman@redhat.com>
AuthorDate:    Wed, 30 Oct 2024 13:52:52 -04:00
Committer:     Peter Zijlstra <peterz@infradead.org>
CommitterDate: Mon, 02 Dec 2024 12:24:28 +01:00

sched/isolation: Consolidate housekeeping cpumasks that are always identical

The housekeeping cpumasks are only set by two boot commandline
parameters: "nohz_full" and "isolcpus". When there is more than one of
"nohz_full" or "isolcpus", the extra ones must have the same CPU list
or the setup will fail partially.

The HK_TYPE_DOMAIN and HK_TYPE_MANAGED_IRQ types are settable by
"isolcpus" only and their settings can be independent of the other
types. The other housekeeping types are all set by "nohz_full" or
"isolcpus=nohz" without a way to set them individually. So they all
have identical cpumasks.

There is actually no point in having different cpumasks for these
"nohz_full" only housekeeping types. Consolidate these types to use the
same cpumask by aliasing them to the same value. If there is a need to
set any of them independently in the future, we can break them out to
their own cpumasks again.

With this change, the number of cpumasks in the housekeeping structure
drops from 9 to 3. Other than that, there should be no other functional
change.

Signed-off-by: Waiman Long <longman@redhat.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Acked-by: Frederic Weisbecker <frederic@kernel.org>
Link: https://lore.kernel.org/r/20241030175253.125248-4-longman@redhat.com
---
 include/linux/sched/isolation.h | 20 +++++++++++++-------
 kernel/sched/isolation.c        | 19 ++++++-------------
 2 files changed, 19 insertions(+), 20 deletions(-)

diff --git a/include/linux/sched/isolation.h b/include/linux/sched/isolation.h
index 499d5e4..d8501f4 100644
--- a/include/linux/sched/isolation.h
+++ b/include/linux/sched/isolation.h
@@ -7,15 +7,21 @@
 #include <linux/tick.h>
 
 enum hk_type {
-	HK_TYPE_TIMER,
-	HK_TYPE_RCU,
-	HK_TYPE_MISC,
-	HK_TYPE_TICK,
 	HK_TYPE_DOMAIN,
-	HK_TYPE_WQ,
 	HK_TYPE_MANAGED_IRQ,
-	HK_TYPE_KTHREAD,
-	HK_TYPE_MAX
+	HK_TYPE_KERNEL_NOISE,
+	HK_TYPE_MAX,
+
+	/*
+	 * The following housekeeping types are only set by the nohz_full
+	 * boot commandline option. So they can share the same value.
+	 */
+	HK_TYPE_TICK    = HK_TYPE_KERNEL_NOISE,
+	HK_TYPE_TIMER   = HK_TYPE_KERNEL_NOISE,
+	HK_TYPE_RCU     = HK_TYPE_KERNEL_NOISE,
+	HK_TYPE_MISC    = HK_TYPE_KERNEL_NOISE,
+	HK_TYPE_WQ      = HK_TYPE_KERNEL_NOISE,
+	HK_TYPE_KTHREAD = HK_TYPE_KERNEL_NOISE
 };
 
 #ifdef CONFIG_CPU_ISOLATION
diff --git a/kernel/sched/isolation.c b/kernel/sched/isolation.c
index 6a68632..81bc8b3 100644
--- a/kernel/sched/isolation.c
+++ b/kernel/sched/isolation.c
@@ -9,14 +9,9 @@
  */
 
 enum hk_flags {
-	HK_FLAG_TIMER		= BIT(HK_TYPE_TIMER),
-	HK_FLAG_RCU		= BIT(HK_TYPE_RCU),
-	HK_FLAG_MISC		= BIT(HK_TYPE_MISC),
-	HK_FLAG_TICK		= BIT(HK_TYPE_TICK),
 	HK_FLAG_DOMAIN		= BIT(HK_TYPE_DOMAIN),
-	HK_FLAG_WQ		= BIT(HK_TYPE_WQ),
 	HK_FLAG_MANAGED_IRQ	= BIT(HK_TYPE_MANAGED_IRQ),
-	HK_FLAG_KTHREAD		= BIT(HK_TYPE_KTHREAD),
+	HK_FLAG_KERNEL_NOISE	= BIT(HK_TYPE_KERNEL_NOISE),
 };
 
 DEFINE_STATIC_KEY_FALSE(housekeeping_overridden);
@@ -96,7 +91,7 @@ void __init housekeeping_init(void)
 
 	static_branch_enable(&housekeeping_overridden);
 
-	if (housekeeping.flags & HK_FLAG_TICK)
+	if (housekeeping.flags & HK_FLAG_KERNEL_NOISE)
 		sched_tick_offload_init();
 
 	for_each_set_bit(type, &housekeeping.flags, HK_TYPE_MAX) {
@@ -120,7 +115,7 @@ static int __init housekeeping_setup(char *str, unsigned long flags)
 	unsigned int first_cpu;
 	int err = 0;
 
-	if ((flags & HK_FLAG_TICK) && !(housekeeping.flags & HK_FLAG_TICK)) {
+	if ((flags & HK_FLAG_KERNEL_NOISE) && !(housekeeping.flags & HK_FLAG_KERNEL_NOISE)) {
 		if (!IS_ENABLED(CONFIG_NO_HZ_FULL)) {
 			pr_warn("Housekeeping: nohz unsupported."
 				" Build with CONFIG_NO_HZ_FULL\n");
@@ -176,7 +171,7 @@ static int __init housekeeping_setup(char *str, unsigned long flags)
 			housekeeping_setup_type(type, housekeeping_staging);
 	}
 
-	if ((flags & HK_FLAG_TICK) && !(housekeeping.flags & HK_FLAG_TICK))
+	if ((flags & HK_FLAG_KERNEL_NOISE) && !(housekeeping.flags & HK_FLAG_KERNEL_NOISE))
 		tick_nohz_full_setup(non_housekeeping_mask);
 
 	housekeeping.flags |= flags;
@@ -194,8 +189,7 @@ static int __init housekeeping_nohz_full_setup(char *str)
 {
 	unsigned long flags;
 
-	flags = HK_FLAG_TICK | HK_FLAG_WQ | HK_FLAG_TIMER | HK_FLAG_RCU |
-		HK_FLAG_MISC | HK_FLAG_KTHREAD;
+	flags = HK_FLAG_KERNEL_NOISE;
 
 	return housekeeping_setup(str, flags);
 }
@@ -214,8 +208,7 @@ static int __init housekeeping_isolcpus_setup(char *str)
 		 */
 		if (!strncmp(str, "nohz,", 5)) {
 			str += 5;
-			flags |= HK_FLAG_TICK | HK_FLAG_WQ | HK_FLAG_TIMER |
-				 HK_FLAG_RCU | HK_FLAG_MISC | HK_FLAG_KTHREAD;
+			flags |= HK_FLAG_KERNEL_NOISE;
 			continue;
 		}
 

[RESEND PATCH v4 4/4] sched: Unify HK_TYPE_{TIMER|TICK|MISC} to HK_TYPE_KERNEL_NOISE

[Waiman Long]

As all the non-domain and non-managed_irq housekeeping types have been
unified to HK_TYPE_KERNEL_NOISE, replace all these references in the
scheduler to use HK_TYPE_KERNEL_NOISE.

Signed-off-by: Waiman Long <longman@redhat.com>
Acked-by: Frederic Weisbecker <frederic@kernel.org>
---
 kernel/sched/core.c | 12 ++++++------
 kernel/sched/fair.c |  5 +++--
 2 files changed, 9 insertions(+), 8 deletions(-)

diff --git a/kernel/sched/core.c b/kernel/sched/core.c
index a7af49b3a337..3412d0046d08 100644
--- a/kernel/sched/core.c
+++ b/kernel/sched/core.c
@@ -1114,13 +1114,13 @@ int get_nohz_timer_target(void)
 	struct sched_domain *sd;
 	const struct cpumask *hk_mask;
 
-	if (housekeeping_cpu(cpu, HK_TYPE_TIMER)) {
+	if (housekeeping_cpu(cpu, HK_TYPE_KERNEL_NOISE)) {
 		if (!idle_cpu(cpu))
 			return cpu;
 		default_cpu = cpu;
 	}
 
-	hk_mask = housekeeping_cpumask(HK_TYPE_TIMER);
+	hk_mask = housekeeping_cpumask(HK_TYPE_KERNEL_NOISE);
 
 	guard(rcu)();
 
@@ -1135,7 +1135,7 @@ int get_nohz_timer_target(void)
 	}
 
 	if (default_cpu == -1)
-		default_cpu = housekeeping_any_cpu(HK_TYPE_TIMER);
+		default_cpu = housekeeping_any_cpu(HK_TYPE_KERNEL_NOISE);
 
 	return default_cpu;
 }
@@ -5526,7 +5526,7 @@ void sched_tick(void)
 	unsigned long hw_pressure;
 	u64 resched_latency;
 
-	if (housekeeping_cpu(cpu, HK_TYPE_TICK))
+	if (housekeeping_cpu(cpu, HK_TYPE_KERNEL_NOISE))
 		arch_scale_freq_tick();
 
 	sched_clock_tick();
@@ -5652,7 +5652,7 @@ static void sched_tick_start(int cpu)
 	int os;
 	struct tick_work *twork;
 
-	if (housekeeping_cpu(cpu, HK_TYPE_TICK))
+	if (housekeeping_cpu(cpu, HK_TYPE_KERNEL_NOISE))
 		return;
 
 	WARN_ON_ONCE(!tick_work_cpu);
@@ -5673,7 +5673,7 @@ static void sched_tick_stop(int cpu)
 	struct tick_work *twork;
 	int os;
 
-	if (housekeeping_cpu(cpu, HK_TYPE_TICK))
+	if (housekeeping_cpu(cpu, HK_TYPE_KERNEL_NOISE))
 		return;
 
 	WARN_ON_ONCE(!tick_work_cpu);
diff --git a/kernel/sched/fair.c b/kernel/sched/fair.c
index f76690c15bfe..08a3d024faf9 100644
--- a/kernel/sched/fair.c
+++ b/kernel/sched/fair.c
@@ -12208,7 +12208,7 @@ static inline int find_new_ilb(void)
 	const struct cpumask *hk_mask;
 	int ilb_cpu;
 
-	hk_mask = housekeeping_cpumask(HK_TYPE_MISC);
+	hk_mask = housekeeping_cpumask(HK_TYPE_KERNEL_NOISE);
 
 	for_each_cpu_and(ilb_cpu, nohz.idle_cpus_mask, hk_mask) {
 
@@ -12226,7 +12226,8 @@ static inline int find_new_ilb(void)
  * Kick a CPU to do the NOHZ balancing, if it is time for it, via a cross-CPU
  * SMP function call (IPI).
  *
- * We pick the first idle CPU in the HK_TYPE_MISC housekeeping set (if there is one).
+ * We pick the first idle CPU in the HK_TYPE_KERNEL_NOISE housekeeping set
+ * (if there is one).
  */
 static void kick_ilb(unsigned int flags)
 {
-- 
2.43.5

[tip: sched/core] sched: Unify HK_TYPE_{TIMER|TICK|MISC} to HK_TYPE_KERNEL_NOISE

[tip-bot2 for Waiman Long]

The following commit has been merged into the sched/core branch of tip:

Commit-ID:     c907cd44a108eff7005a2b5689bb91f50637df8b
Gitweb:        https://git.kernel.org/tip/c907cd44a108eff7005a2b5689bb91f50637df8b
Author:        Waiman Long <longman@redhat.com>
AuthorDate:    Wed, 30 Oct 2024 13:52:53 -04:00
Committer:     Peter Zijlstra <peterz@infradead.org>
CommitterDate: Mon, 02 Dec 2024 12:24:28 +01:00

sched: Unify HK_TYPE_{TIMER|TICK|MISC} to HK_TYPE_KERNEL_NOISE

As all the non-domain and non-managed_irq housekeeping types have been
unified to HK_TYPE_KERNEL_NOISE, replace all these references in the
scheduler to use HK_TYPE_KERNEL_NOISE.

Signed-off-by: Waiman Long <longman@redhat.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Acked-by: Frederic Weisbecker <frederic@kernel.org>
Link: https://lore.kernel.org/r/20241030175253.125248-5-longman@redhat.com
---
 kernel/sched/core.c | 12 ++++++------
 kernel/sched/fair.c |  5 +++--
 2 files changed, 9 insertions(+), 8 deletions(-)

diff --git a/kernel/sched/core.c b/kernel/sched/core.c
index 1dee3f5..5fbec67 100644
--- a/kernel/sched/core.c
+++ b/kernel/sched/core.c
@@ -1170,13 +1170,13 @@ int get_nohz_timer_target(void)
 	struct sched_domain *sd;
 	const struct cpumask *hk_mask;
 
-	if (housekeeping_cpu(cpu, HK_TYPE_TIMER)) {
+	if (housekeeping_cpu(cpu, HK_TYPE_KERNEL_NOISE)) {
 		if (!idle_cpu(cpu))
 			return cpu;
 		default_cpu = cpu;
 	}
 
-	hk_mask = housekeeping_cpumask(HK_TYPE_TIMER);
+	hk_mask = housekeeping_cpumask(HK_TYPE_KERNEL_NOISE);
 
 	guard(rcu)();
 
@@ -1191,7 +1191,7 @@ int get_nohz_timer_target(void)
 	}
 
 	if (default_cpu == -1)
-		default_cpu = housekeeping_any_cpu(HK_TYPE_TIMER);
+		default_cpu = housekeeping_any_cpu(HK_TYPE_KERNEL_NOISE);
 
 	return default_cpu;
 }
@@ -5634,7 +5634,7 @@ void sched_tick(void)
 	unsigned long hw_pressure;
 	u64 resched_latency;
 
-	if (housekeeping_cpu(cpu, HK_TYPE_TICK))
+	if (housekeeping_cpu(cpu, HK_TYPE_KERNEL_NOISE))
 		arch_scale_freq_tick();
 
 	sched_clock_tick();
@@ -5773,7 +5773,7 @@ static void sched_tick_start(int cpu)
 	int os;
 	struct tick_work *twork;
 
-	if (housekeeping_cpu(cpu, HK_TYPE_TICK))
+	if (housekeeping_cpu(cpu, HK_TYPE_KERNEL_NOISE))
 		return;
 
 	WARN_ON_ONCE(!tick_work_cpu);
@@ -5794,7 +5794,7 @@ static void sched_tick_stop(int cpu)
 	struct tick_work *twork;
 	int os;
 
-	if (housekeeping_cpu(cpu, HK_TYPE_TICK))
+	if (housekeeping_cpu(cpu, HK_TYPE_KERNEL_NOISE))
 		return;
 
 	WARN_ON_ONCE(!tick_work_cpu);
diff --git a/kernel/sched/fair.c b/kernel/sched/fair.c
index ef30226..d5127d9 100644
--- a/kernel/sched/fair.c
+++ b/kernel/sched/fair.c
@@ -12203,7 +12203,7 @@ static inline int find_new_ilb(void)
 	const struct cpumask *hk_mask;
 	int ilb_cpu;
 
-	hk_mask = housekeeping_cpumask(HK_TYPE_MISC);
+	hk_mask = housekeeping_cpumask(HK_TYPE_KERNEL_NOISE);
 
 	for_each_cpu_and(ilb_cpu, nohz.idle_cpus_mask, hk_mask) {
 
@@ -12221,7 +12221,8 @@ static inline int find_new_ilb(void)
  * Kick a CPU to do the NOHZ balancing, if it is time for it, via a cross-CPU
  * SMP function call (IPI).
  *
- * We pick the first idle CPU in the HK_TYPE_MISC housekeeping set (if there is one).
+ * We pick the first idle CPU in the HK_TYPE_KERNEL_NOISE housekeeping set
+ * (if there is one).
  */
 static void kick_ilb(unsigned int flags)
 {