[PATCH] sched/numa: Add statistics of numa balance task migration and swap

[PATCH] sched/numa: Add statistics of numa balance task migration and swap

[Chen Yu]

On system with NUMA balancing enabled, it is found that tracking
the task activities due to NUMA balancing is helpful. NUMA balancing
has two mechanisms for task migration: one is to migrate the task to
an idle CPU in its preferred node, the other is to swap tasks on
different nodes if they are on each other's preferred node.

The kernel already has NUMA page migration statistics in
/sys/fs/cgroup/mytest/memory.stat and /proc/{PID}/sched.
but does not have statistics for task migration/swap.
Add the task migration and swap count accordingly.

The following two new fields:

numa_task_migrated
numa_task_swapped

will be displayed in both
/sys/fs/cgroup/{GROUP}/memory.stat and /proc/{PID}/sched

Previous RFC version can be found here:
https://lore.kernel.org/lkml/1847c5ef828ad4835a35e3a54b88d2e13bce0eea.1740483690.git.yu.c.chen@intel.com/

Signed-off-by: Chen Yu <yu.c.chen@intel.com>
---
RFC->v1: Rename the nr_numa_task_migrated to
         numa_task_migrated, and nr_numa_task_swapped
         numa_task_swapped in /proc/{PID}/sched,
         so both cgroup's memory.stat and task's
         sched have the same field name.
---
 include/linux/sched.h         |  4 ++++
 include/linux/vm_event_item.h |  2 ++
 kernel/sched/core.c           | 10 ++++++++--
 kernel/sched/debug.c          |  4 ++++
 mm/memcontrol.c               |  2 ++
 mm/vmstat.c                   |  2 ++
 6 files changed, 22 insertions(+), 2 deletions(-)

diff --git a/include/linux/sched.h b/include/linux/sched.h
index 0785268c76f8..9623e5300453 100644
--- a/include/linux/sched.h
+++ b/include/linux/sched.h
@@ -532,6 +532,10 @@ struct sched_statistics {
 	u64				nr_failed_migrations_running;
 	u64				nr_failed_migrations_hot;
 	u64				nr_forced_migrations;
+#ifdef CONFIG_NUMA_BALANCING
+	u64				numa_task_migrated;
+	u64				numa_task_swapped;
+#endif
 
 	u64				nr_wakeups;
 	u64				nr_wakeups_sync;
diff --git a/include/linux/vm_event_item.h b/include/linux/vm_event_item.h
index f70d0958095c..aef817474781 100644
--- a/include/linux/vm_event_item.h
+++ b/include/linux/vm_event_item.h
@@ -64,6 +64,8 @@ enum vm_event_item { PGPGIN, PGPGOUT, PSWPIN, PSWPOUT,
 		NUMA_HINT_FAULTS,
 		NUMA_HINT_FAULTS_LOCAL,
 		NUMA_PAGE_MIGRATE,
+		NUMA_TASK_MIGRATE,
+		NUMA_TASK_SWAP,
 #endif
 #ifdef CONFIG_MIGRATION
 		PGMIGRATE_SUCCESS, PGMIGRATE_FAIL,
diff --git a/kernel/sched/core.c b/kernel/sched/core.c
index c86c05264719..314d5cbce2b6 100644
--- a/kernel/sched/core.c
+++ b/kernel/sched/core.c
@@ -3348,6 +3348,11 @@ void set_task_cpu(struct task_struct *p, unsigned int new_cpu)
 #ifdef CONFIG_NUMA_BALANCING
 static void __migrate_swap_task(struct task_struct *p, int cpu)
 {
+	__schedstat_inc(p->stats.numa_task_swapped);
+
+	if (p->mm)
+		count_memcg_events_mm(p->mm, NUMA_TASK_SWAP, 1);
+
 	if (task_on_rq_queued(p)) {
 		struct rq *src_rq, *dst_rq;
 		struct rq_flags srf, drf;
@@ -7948,8 +7953,9 @@ int migrate_task_to(struct task_struct *p, int target_cpu)
 	if (!cpumask_test_cpu(target_cpu, p->cpus_ptr))
 		return -EINVAL;
 
-	/* TODO: This is not properly updating schedstats */
-
+	__schedstat_inc(p->stats.numa_task_migrated);
+	if (p->mm)
+		count_memcg_events_mm(p->mm, NUMA_TASK_MIGRATE, 1);
 	trace_sched_move_numa(p, curr_cpu, target_cpu);
 	return stop_one_cpu(curr_cpu, migration_cpu_stop, &arg);
 }
diff --git a/kernel/sched/debug.c b/kernel/sched/debug.c
index 56ae54e0ce6a..f971c2af7912 100644
--- a/kernel/sched/debug.c
+++ b/kernel/sched/debug.c
@@ -1206,6 +1206,10 @@ void proc_sched_show_task(struct task_struct *p, struct pid_namespace *ns,
 		P_SCHEDSTAT(nr_failed_migrations_running);
 		P_SCHEDSTAT(nr_failed_migrations_hot);
 		P_SCHEDSTAT(nr_forced_migrations);
+#ifdef CONFIG_NUMA_BALANCING
+		P_SCHEDSTAT(numa_task_migrated);
+		P_SCHEDSTAT(numa_task_swapped);
+#endif
 		P_SCHEDSTAT(nr_wakeups);
 		P_SCHEDSTAT(nr_wakeups_sync);
 		P_SCHEDSTAT(nr_wakeups_migrate);
diff --git a/mm/memcontrol.c b/mm/memcontrol.c
index 4de6acb9b8ec..1656c90b2381 100644
--- a/mm/memcontrol.c
+++ b/mm/memcontrol.c
@@ -460,6 +460,8 @@ static const unsigned int memcg_vm_event_stat[] = {
 	NUMA_PAGE_MIGRATE,
 	NUMA_PTE_UPDATES,
 	NUMA_HINT_FAULTS,
+	NUMA_TASK_MIGRATE,
+	NUMA_TASK_SWAP,
 #endif
 };
 
diff --git a/mm/vmstat.c b/mm/vmstat.c
index 16bfe1c694dd..7de1583a63c9 100644
--- a/mm/vmstat.c
+++ b/mm/vmstat.c
@@ -1339,6 +1339,8 @@ const char * const vmstat_text[] = {
 	"numa_hint_faults",
 	"numa_hint_faults_local",
 	"numa_pages_migrated",
+	"numa_task_migrated",
+	"numa_task_swapped",
 #endif
 #ifdef CONFIG_MIGRATION
 	"pgmigrate_success",
-- 
2.25.1

Re: [PATCH] sched/numa: Add statistics of numa balance task migration and swap

[Michal Koutný]

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Hello Chen.

On Wed, Apr 02, 2025 at 09:06:11AM +0800, Chen Yu <yu.c.chen@intel.com> wrote:
> On system with NUMA balancing enabled, it is found that tracking
> the task activities due to NUMA balancing is helpful.
...
> The following two new fields:
> 
> numa_task_migrated
> numa_task_swapped
> 
> will be displayed in both
> /sys/fs/cgroup/{GROUP}/memory.stat and /proc/{PID}/sched

Why is the field /proc/$pid/sched not enough?

Also, you may want to update Documentation/admin-guide/cgroup-v2.rst
too.

Thanks,
Michal

[-- Attachment #2: signature.asc --]
[-- Type: application/pgp-signature, Size: 228 bytes --]

Re: [PATCH] sched/numa: Add statistics of numa balance task migration and swap

[Madadi Vineeth Reddy]

Hi Chen Yu,

On 02/04/25 06:36, Chen Yu wrote:
> On system with NUMA balancing enabled, it is found that tracking
> the task activities due to NUMA balancing is helpful. NUMA balancing
> has two mechanisms for task migration: one is to migrate the task to
> an idle CPU in its preferred node, the other is to swap tasks on
> different nodes if they are on each other's preferred node.
> 
> The kernel already has NUMA page migration statistics in
> /sys/fs/cgroup/mytest/memory.stat and /proc/{PID}/sched.
> but does not have statistics for task migration/swap.
> Add the task migration and swap count accordingly.
> 
> The following two new fields:
> 
> numa_task_migrated
> numa_task_swapped
> 
> will be displayed in both
> /sys/fs/cgroup/{GROUP}/memory.stat and /proc/{PID}/sched

I applied this patch, but I still don't see the two new fields
in /proc/{PID}/sched.

Am I missing any additional steps?

Thanks,
Madadi Vineeth Reddy

> 
> Previous RFC version can be found here:
> https://lore.kernel.org/lkml/1847c5ef828ad4835a35e3a54b88d2e13bce0eea.1740483690.git.yu.c.chen@intel.com/
> 
> Signed-off-by: Chen Yu <yu.c.chen@intel.com>
> ---
> RFC->v1: Rename the nr_numa_task_migrated to
>          numa_task_migrated, and nr_numa_task_swapped
>          numa_task_swapped in /proc/{PID}/sched,
>          so both cgroup's memory.stat and task's
>          sched have the same field name.
> ---
>  include/linux/sched.h         |  4 ++++
>  include/linux/vm_event_item.h |  2 ++
>  kernel/sched/core.c           | 10 ++++++++--
>  kernel/sched/debug.c          |  4 ++++
>  mm/memcontrol.c               |  2 ++
>  mm/vmstat.c                   |  2 ++
>  6 files changed, 22 insertions(+), 2 deletions(-)

Re: [PATCH] sched/numa: Add statistics of numa balance task migration and swap

[K Prateek Nayak]

On 4/2/2025 7:03 PM, Madadi Vineeth Reddy wrote:
> Hi Chen Yu,
> 
> On 02/04/25 06:36, Chen Yu wrote:
>> On system with NUMA balancing enabled, it is found that tracking
>> the task activities due to NUMA balancing is helpful. NUMA balancing
>> has two mechanisms for task migration: one is to migrate the task to
>> an idle CPU in its preferred node, the other is to swap tasks on
>> different nodes if they are on each other's preferred node.
>>
>> The kernel already has NUMA page migration statistics in
>> /sys/fs/cgroup/mytest/memory.stat and /proc/{PID}/sched.
>> but does not have statistics for task migration/swap.
>> Add the task migration and swap count accordingly.
>>
>> The following two new fields:
>>
>> numa_task_migrated
>> numa_task_swapped
>>
>> will be displayed in both
>> /sys/fs/cgroup/{GROUP}/memory.stat and /proc/{PID}/sched
> 
> I applied this patch, but I still don't see the two new fields
> in /proc/{PID}/sched.
> 
> Am I missing any additional steps?

You also need to enable schedstats:

echo 1 > /proc/sys/kernel/sched_schedstats

After that it should be visible:

$ cat /proc/4030/sched
sched-messaging (4030, #threads: 641)
-------------------------------------------------------------------
se.exec_start                                :        283818.948537

...

nr_forced_migrations                         :                    0
numa_task_migrated                           :                    0
numa_task_swapped                            :                    0
nr_wakeups                                   :                    0

...

-- 
Thanks and Regards,
Prateek

> 
> Thanks,
> Madadi Vineeth Reddy
> 
>>
>> Previous RFC version can be found here:
>> https://lore.kernel.org/lkml/1847c5ef828ad4835a35e3a54b88d2e13bce0eea.1740483690.git.yu.c.chen@intel.com/
>>
>> Signed-off-by: Chen Yu <yu.c.chen@intel.com>
>> ---
>> RFC->v1: Rename the nr_numa_task_migrated to
>>           numa_task_migrated, and nr_numa_task_swapped
>>           numa_task_swapped in /proc/{PID}/sched,
>>           so both cgroup's memory.stat and task's
>>           sched have the same field name.
>> ---
>>   include/linux/sched.h         |  4 ++++
>>   include/linux/vm_event_item.h |  2 ++
>>   kernel/sched/core.c           | 10 ++++++++--
>>   kernel/sched/debug.c          |  4 ++++
>>   mm/memcontrol.c               |  2 ++
>>   mm/vmstat.c                   |  2 ++
>>   6 files changed, 22 insertions(+), 2 deletions(-)
> 
> 

Re: [PATCH] sched/numa: Add statistics of numa balance task migration and swap

[K Prateek Nayak]

Hello Chenyu,

On 4/2/2025 6:36 AM, Chen Yu wrote:
> On system with NUMA balancing enabled, it is found that tracking
> the task activities due to NUMA balancing is helpful. NUMA balancing
> has two mechanisms for task migration: one is to migrate the task to
> an idle CPU in its preferred node, the other is to swap tasks on
> different nodes if they are on each other's preferred node.
> 
> The kernel already has NUMA page migration statistics in
> /sys/fs/cgroup/mytest/memory.stat and /proc/{PID}/sched.
> but does not have statistics for task migration/swap.
> Add the task migration and swap count accordingly.
> 
> The following two new fields:
> 
> numa_task_migrated
> numa_task_swapped
> 
> will be displayed in both
> /sys/fs/cgroup/{GROUP}/memory.stat and /proc/{PID}/sched

Running sched-messaging with schedstats enabled, I could see both
"numa_task_migrated" and "numa_task_swapped" being populated for the
sched-messaging threads:

$ for i in $(ls /proc/4030/task/); do grep "numa_task_migrated" /proc/$i/sched; done | tr -s ' ' | cut -d ' ' -f3 | sort | uniq -c
     400 0
     231 1
      10 2

$ for i in $(ls /proc/4030/task/); do grep "numa_task_swapped" /proc/$i/sched; done | tr -s ' ' | cut -d ' ' -f3 | sort | uniq -c
     389 0
     193 1
      47 2
      11 3
       1 4

> 
> Previous RFC version can be found here:
> https://lore.kernel.org/lkml/1847c5ef828ad4835a35e3a54b88d2e13bce0eea.1740483690.git.yu.c.chen@intel.com/
> 
> Signed-off-by: Chen Yu <yu.c.chen@intel.com>

Feel free to add:

Tested-by: K Prateek Nayak <kprateek.nayak@amd.com>

-- 
Thanks and Regards,
Prateek

> ---
> RFC->v1: Rename the nr_numa_task_migrated to
>           numa_task_migrated, and nr_numa_task_swapped
>           numa_task_swapped in /proc/{PID}/sched,
>           so both cgroup's memory.stat and task's
>           sched have the same field name.
>

[..snip..]

Re: [PATCH] sched/numa: Add statistics of numa balance task migration and swap

[K Prateek Nayak]

Hello Michal,

On 4/2/2025 6:54 PM, Michal Koutný wrote:
> Hello Chen.
> 
> On Wed, Apr 02, 2025 at 09:06:11AM +0800, Chen Yu <yu.c.chen@intel.com> wrote:
>> On system with NUMA balancing enabled, it is found that tracking
>> the task activities due to NUMA balancing is helpful.
> ...
>> The following two new fields:
>>
>> numa_task_migrated
>> numa_task_swapped
>>
>> will be displayed in both
>> /sys/fs/cgroup/{GROUP}/memory.stat and /proc/{PID}/sched
> 
> Why is the field /proc/$pid/sched not enough?

The /proc/$pid/sched accounting is only done when schedstats are
enabled. memcg users might want to track it separately without relying
on schedstats which also enables a bunch of other scheduler related
stats collection adding more overheads.

> 
> Also, you may want to update Documentation/admin-guide/cgroup-v2.rst
> too.
> 
> Thanks,
> Michal

-- 
Thanks and Regards,
Prateek

Re: [PATCH] sched/numa: Add statistics of numa balance task migration and swap

[Madadi Vineeth Reddy]

On 02/04/25 22:53, K Prateek Nayak wrote:
> On 4/2/2025 7:03 PM, Madadi Vineeth Reddy wrote:
>> Hi Chen Yu,
>>
>> On 02/04/25 06:36, Chen Yu wrote:
>>> On system with NUMA balancing enabled, it is found that tracking
>>> the task activities due to NUMA balancing is helpful. NUMA balancing
>>> has two mechanisms for task migration: one is to migrate the task to
>>> an idle CPU in its preferred node, the other is to swap tasks on
>>> different nodes if they are on each other's preferred node.
>>>
>>> The kernel already has NUMA page migration statistics in
>>> /sys/fs/cgroup/mytest/memory.stat and /proc/{PID}/sched.
>>> but does not have statistics for task migration/swap.
>>> Add the task migration and swap count accordingly.
>>>
>>> The following two new fields:
>>>
>>> numa_task_migrated
>>> numa_task_swapped
>>>
>>> will be displayed in both
>>> /sys/fs/cgroup/{GROUP}/memory.stat and /proc/{PID}/sched
>>
>> I applied this patch, but I still don't see the two new fields
>> in /proc/{PID}/sched.
>>
>> Am I missing any additional steps?
> 
> You also need to enable schedstats:
> 
> echo 1 > /proc/sys/kernel/sched_schedstats
> 
> After that it should be visible:

Thanks, Prateek! I had missed enabling schedstats. Now that it's enabled,
I can see the fields.

Thanks,
Madadi Vineeth Reddy 

> 
> $ cat /proc/4030/sched
> sched-messaging (4030, #threads: 641)
> -------------------------------------------------------------------
> se.exec_start                                :        283818.948537
> 
> ...
> 
> nr_forced_migrations                         :                    0
> numa_task_migrated                           :                    0
> numa_task_swapped                            :                    0
> nr_wakeups                                   :                    0
> 
> ...
> 

Re: [PATCH] sched/numa: Add statistics of numa balance task migration and swap

[Madadi Vineeth Reddy]

Hi Chen Yu,

On 02/04/25 06:36, Chen Yu wrote:
> On system with NUMA balancing enabled, it is found that tracking
> the task activities due to NUMA balancing is helpful. NUMA balancing
> has two mechanisms for task migration: one is to migrate the task to
> an idle CPU in its preferred node, the other is to swap tasks on
> different nodes if they are on each other's preferred node.
> 
> The kernel already has NUMA page migration statistics in
> /sys/fs/cgroup/mytest/memory.stat and /proc/{PID}/sched.
> but does not have statistics for task migration/swap.
> Add the task migration and swap count accordingly.
> 
> The following two new fields:
> 
> numa_task_migrated
> numa_task_swapped
> 
> will be displayed in both
> /sys/fs/cgroup/{GROUP}/memory.stat and /proc/{PID}/sched

I was able to see the fields and their corresponding values for schbench:

numa_task_swapped                            :                    2
numa_task_migrated                           :                    0
numa_task_swapped                            :                    1
numa_task_migrated                           :                    0
numa_task_swapped                            :                    0
numa_task_migrated                           :                    0
numa_task_swapped                            :                    1

Tested-by: Madadi Vineeth Reddy <vineethr@linux.ibm.com>

Thanks,
Madadi Vineeth Reddy

> Previous RFC version can be found here:
> https://lore.kernel.org/lkml/1847c5ef828ad4835a35e3a54b88d2e13bce0eea.1740483690.git.yu.c.chen@intel.com/
> 
> Signed-off-by: Chen Yu <yu.c.chen@intel.com>
> ---
> RFC->v1: Rename the nr_numa_task_migrated to
>          numa_task_migrated, and nr_numa_task_swapped
>          numa_task_swapped in /proc/{PID}/sched,
>          so both cgroup's memory.stat and task's
>          sched have the same field name.
> ---
>  include/linux/sched.h         |  4 ++++
>  include/linux/vm_event_item.h |  2 ++
>  kernel/sched/core.c           | 10 ++++++++--
>  kernel/sched/debug.c          |  4 ++++
>  mm/memcontrol.c               |  2 ++
>  mm/vmstat.c                   |  2 ++
>  6 files changed, 22 insertions(+), 2 deletions(-)

Re: [PATCH] sched/numa: Add statistics of numa balance task migration and swap

[Chen, Yu C]

Hi Michal,

thanks for taking a look at this,

On 4/2/2025 9:24 PM, Michal Koutný wrote:
> Hello Chen.
> 
> On Wed, Apr 02, 2025 at 09:06:11AM +0800, Chen Yu <yu.c.chen@intel.com> wrote:
>> On system with NUMA balancing enabled, it is found that tracking
>> the task activities due to NUMA balancing is helpful.
> ...
>> The following two new fields:
>>
>> numa_task_migrated
>> numa_task_swapped
>>
>> will be displayed in both
>> /sys/fs/cgroup/{GROUP}/memory.stat and /proc/{PID}/sched
> 
> Why is the field /proc/$pid/sched not enough?
> 

In the context of NUMA balancing, it would be helpful to not only 
monitor on the activities of individual task/thread but also the 
resource usage and task migrations at the group level - which helps us 
quickly evaluate the performance and resource usage of the container - 
like per memcg numa_pages_migrated, numa_pte_updates introduced in
commit f77f0c751478 ("mm,memcg: provide per-cgroup counters for NUMA 
balancing operations"). Yes, we can iterate the /proc/$pid/sched to
find the accumulated NUMA stat, and the introduction of per - cgroup 
numa stat can help users more conveniently track the overall data of the 
workload.

Besides, I'm considering evaluating the per - cgroup NUMA balance 
control[1] to help users do fine - grain control per workload. This per 
- cgroup NUMA balance stat could be used to evaluate the efficiency of 
per - cgroup NUMA balance.

> Also, you may want to update Documentation/admin-guide/cgroup-v2.rst
> too.

Got it, will do in next version.

[1] 
https://lore.kernel.org/lkml/b3f1f6c478127a38b9091a8341374ba160d25c5a.1740483690.git.yu.c.chen@intel.com/

thanks,
Chenyu

> 
> Thanks,
> Michal

Re: [PATCH] sched/numa: Add statistics of numa balance task migration and swap

[Chen, Yu C]

On 4/3/2025 1:35 AM, K Prateek Nayak wrote:
> Hello Chenyu,
> 
> On 4/2/2025 6:36 AM, Chen Yu wrote:
>> On system with NUMA balancing enabled, it is found that tracking
>> the task activities due to NUMA balancing is helpful. NUMA balancing
>> has two mechanisms for task migration: one is to migrate the task to
>> an idle CPU in its preferred node, the other is to swap tasks on
>> different nodes if they are on each other's preferred node.
>>
>> The kernel already has NUMA page migration statistics in
>> /sys/fs/cgroup/mytest/memory.stat and /proc/{PID}/sched.
>> but does not have statistics for task migration/swap.
>> Add the task migration and swap count accordingly.
>>
>> The following two new fields:
>>
>> numa_task_migrated
>> numa_task_swapped
>>
>> will be displayed in both
>> /sys/fs/cgroup/{GROUP}/memory.stat and /proc/{PID}/sched
> 
> Running sched-messaging with schedstats enabled, I could see both
> "numa_task_migrated" and "numa_task_swapped" being populated for the
> sched-messaging threads:
> 
> $ for i in $(ls /proc/4030/task/); do grep "numa_task_migrated" /proc/ 
> $i/sched; done | tr -s ' ' | cut -d ' ' -f3 | sort | uniq -c
>      400 0
>      231 1
>       10 2
> 
> $ for i in $(ls /proc/4030/task/); do grep "numa_task_swapped" /proc/$i/ 
> sched; done | tr -s ' ' | cut -d ' ' -f3 | sort | uniq -c
>      389 0
>      193 1
>       47 2
>       11 3
>        1 4
> 
>>
>> Previous RFC version can be found here:
>> https://lore.kernel.org/ 
>> lkml/1847c5ef828ad4835a35e3a54b88d2e13bce0eea.1740483690.git.yu.c.chen@intel.com/
>>
>> Signed-off-by: Chen Yu <yu.c.chen@intel.com>
> 
> Feel free to add:
> 
> Tested-by: K Prateek Nayak <kprateek.nayak@amd.com>
> 


Thanks Prateek!

Thanks,
Chenyu

Re: [PATCH] sched/numa: Add statistics of numa balance task migration and swap

[Chen, Yu C]

On 4/3/2025 2:50 AM, Madadi Vineeth Reddy wrote:
> Hi Chen Yu,
> 
> On 02/04/25 06:36, Chen Yu wrote:
>> On system with NUMA balancing enabled, it is found that tracking
>> the task activities due to NUMA balancing is helpful. NUMA balancing
>> has two mechanisms for task migration: one is to migrate the task to
>> an idle CPU in its preferred node, the other is to swap tasks on
>> different nodes if they are on each other's preferred node.
>>
>> The kernel already has NUMA page migration statistics in
>> /sys/fs/cgroup/mytest/memory.stat and /proc/{PID}/sched.
>> but does not have statistics for task migration/swap.
>> Add the task migration and swap count accordingly.
>>
>> The following two new fields:
>>
>> numa_task_migrated
>> numa_task_swapped
>>
>> will be displayed in both
>> /sys/fs/cgroup/{GROUP}/memory.stat and /proc/{PID}/sched
> 
> I was able to see the fields and their corresponding values for schbench:
> 
> numa_task_swapped                            :                    2
> numa_task_migrated                           :                    0
> numa_task_swapped                            :                    1
> numa_task_migrated                           :                    0
> numa_task_swapped                            :                    0
> numa_task_migrated                           :                    0
> numa_task_swapped                            :                    1
> 
> Tested-by: Madadi Vineeth Reddy <vineethr@linux.ibm.com>
> 

Yes, the sysfs schedstat has to be enabled. Thanks for your test, Madadi!

thanks,
Chenyu

> Thanks,
> Madadi Vineeth Reddy
> 
>> Previous RFC version can be found here:
>> https://lore.kernel.org/lkml/1847c5ef828ad4835a35e3a54b88d2e13bce0eea.1740483690.git.yu.c.chen@intel.com/
>>
>> Signed-off-by: Chen Yu <yu.c.chen@intel.com>
>> ---
>> RFC->v1: Rename the nr_numa_task_migrated to
>>           numa_task_migrated, and nr_numa_task_swapped
>>           numa_task_swapped in /proc/{PID}/sched,
>>           so both cgroup's memory.stat and task's
>>           sched have the same field name.
>> ---
>>   include/linux/sched.h         |  4 ++++
>>   include/linux/vm_event_item.h |  2 ++
>>   kernel/sched/core.c           | 10 ++++++++--
>>   kernel/sched/debug.c          |  4 ++++
>>   mm/memcontrol.c               |  2 ++
>>   mm/vmstat.c                   |  2 ++
>>   6 files changed, 22 insertions(+), 2 deletions(-)

Re: [PATCH] sched/numa: Add statistics of numa balance task migration and swap

[Michal Koutný]

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On Wed, Apr 02, 2025 at 11:13:03PM +0530, K Prateek Nayak <kprateek.nayak@amd.com> wrote:
> The /proc/$pid/sched accounting is only done when schedstats are
> enabled. memcg users might want to track it separately without relying
> on schedstats which also enables a bunch of other scheduler related
> stats collection adding more overheads.

.oO(memory.[numa_]stat could end up with something similar since not all
users are interested in all fields but all users are affected by added
fields)

Thanks,
Michal

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Re: [PATCH] sched/numa: Add statistics of numa balance task migration and swap

[Michal Koutný]

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On Thu, Apr 03, 2025 at 10:47:44AM +0800, "Chen, Yu C" <yu.c.chen@intel.com> wrote:
> In the context of NUMA balancing, it would be helpful to not only monitor on
> the activities of individual task/thread but also the resource usage and
> task migrations at the group level - which helps us quickly evaluate the
> performance and resource usage of the container - like per memcg
> numa_pages_migrated, numa_pte_updates introduced in

Somehow I thought that these are the useful metrics (amount of misplaced
memory) and the aggregated task stats aren't interesting (they'd be more
or less proportion of total number of tasks in the group and you don't
know which task it was).

> Got it, will do in next version.

OK.

Thanks,
Michal

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