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@xxxxxxxxx/
> >
> > Signed-off-by: Chen Yu <yu.c.chen@xxxxxxxxx>
> > ---
> > 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(-)