Re: [PATCH] memcg: net: track network throttling due to memcg memory pressure

[Shakeel Butt <shakeel.butt@linux.dev>]

On Wed, Oct 15, 2025 at 10:46:54PM -0700, Kuniyuki Iwashima wrote:
> On Wed, Oct 15, 2025 at 6:40 PM Roman Gushchin <roman.gushchin@linux.dev> wrote:
> >
> > Shakeel Butt <shakeel.butt@linux.dev> writes:
> >
> > > The kernel can throttle network sockets if the memory cgroup associated
> > > with the corresponding socket is under memory pressure. The throttling
> > > actions include clamping the transmit window, failing to expand receive
> > > or send buffers, aggressively prune out-of-order receive queue, FIN
> > > deferred to a retransmitted packet and more. Let's add memcg metric to
> > > indicate track such throttling actions.
> > >
> > > At the moment memcg memory pressure is defined through vmpressure and in
> > > future it may be defined using PSI or we may add more flexible way for
> > > the users to define memory pressure, maybe through ebpf. However the
> > > potential throttling actions will remain the same, so this newly
> > > introduced metric will continue to track throttling actions irrespective
> > > of how memcg memory pressure is defined.
> > >
> > > Signed-off-by: Shakeel Butt <shakeel.butt@linux.dev>
> > > ---
> > >  Documentation/admin-guide/cgroup-v2.rst | 4 ++++
> > >  include/linux/memcontrol.h              | 1 +
> > >  include/net/sock.h                      | 6 +++++-
> > >  kernel/cgroup/cgroup.c                  | 1 +
> > >  mm/memcontrol.c                         | 3 +++
> > >  5 files changed, 14 insertions(+), 1 deletion(-)
> > >
> > > diff --git a/Documentation/admin-guide/cgroup-v2.rst b/Documentation/admin-guide/cgroup-v2.rst
> > > index 0e6c67ac585a..057ee95e43ef 100644
> > > --- a/Documentation/admin-guide/cgroup-v2.rst
> > > +++ b/Documentation/admin-guide/cgroup-v2.rst
> > > @@ -1515,6 +1515,10 @@ The following nested keys are defined.
> > >            oom_group_kill
> > >                  The number of times a group OOM has occurred.
> > >
> > > +          socks_throttled
> > > +                The number of times network sockets associated with
> > > +                this cgroup are throttled.
> >
> > I'd prefer sockets_throttled or sock_throttled. And same for the
> > constant name.
> >
> > Otherwise,
> > Acked-by: Roman Gushchin <roman.gushchin@linux.dev>
> 
> +1 for sock_ like "sock" in memory.stat and its MEMCG_SOCK.
> 
> Reviewed-by: Kuniyuki Iwashima <kuniyu@google.com>
> 

Thanks Roman and Kuniyuki, will change the name to sock_throttled in v2.