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Mercier" Date: Wed, 14 Aug 2024 14:01:06 -0700 Message-ID: Subject: Re: [PATCH 4/4] memcg: initiate deprecation of pressure_level To: Shakeel Butt Cc: Andrew Morton , Johannes Weiner , Michal Hocko , Roman Gushchin , Muchun Song , linux-mm@kvack.org, linux-kernel@vger.kernel.org, Meta kernel team , cgroups@vger.kernel.org Content-Type: text/plain; charset="UTF-8" Content-Transfer-Encoding: quoted-printable X-Rspamd-Server: rspam07 X-Rspamd-Queue-Id: DD68240007 X-Stat-Signature: 1ddhgsd9asausiybeu4okfnsx78wewb8 X-Rspam-User: X-HE-Tag: 1723669282-13994 X-HE-Meta: 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 LZgYSMTg cr56CGo5BZWtuypFgFBwzcTr8uweNud5q0YwCn4KX7IB4QwNpz25uk0sj5i0Ua5LXIMkswQCrYFl1V0Z47E4gUJmQobFmL9x28E0msSn8NrLiFD9Ktz9lfPHVP9CVK/1unbGm/ulLi36fC3CWuxOXe2sO0zZ4q69i6+Wt5AESGd3b+A5p7KdoZFkhL1qddPkULy89enq/XhT6B8tVb/cWFgelz60xLAcgPAs6F3iNsEMQpGcFiad76Sqwkb7MJpK2cgIic49a/UrrC4UBqiZx/pE0Fw== X-Bogosity: Ham, tests=bogofilter, spamicity=0.000000, version=1.2.4 Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: List-Subscribe: List-Unsubscribe: On Wed, Aug 14, 2024 at 1:29=E2=80=AFPM Shakeel Butt wrote: > > The pressure_level in memcg v1 provides memory pressure notifications to > the user space. At the moment it provides notifications for three levels > of memory pressure i.e. low, medium and critical, which are defined > based on internal memory reclaim implementation details. More > specifically the ratio or scanned and reclaimed pages during a memory > reclaim. However this is not robust as there are workloads with mostly > unreclaimable user memory or kernel memory. > > For v2, the users can use PSI for memory pressure status of the system > or the cgroup. Let's start the deprecation process for pressure_level > and add warnings to gather the info on how the current users are using > this interface and how they can be used to PSI. > > Signed-off-by: Shakeel Butt > --- > Documentation/admin-guide/cgroup-v1/memory.rst | 8 ++++++-- > mm/memcontrol-v1.c | 3 +++ > 2 files changed, 9 insertions(+), 2 deletions(-) > > diff --git a/Documentation/admin-guide/cgroup-v1/memory.rst b/Documentati= on/admin-guide/cgroup-v1/memory.rst > index 74cea6712d06..8ec1faf08b6b 100644 > --- a/Documentation/admin-guide/cgroup-v1/memory.rst > +++ b/Documentation/admin-guide/cgroup-v1/memory.rst > @@ -86,6 +86,8 @@ Brief summary of control files. > used. > memory.force_empty trigger forced page reclaim > memory.pressure_level set memory pressure notifications > + This knob is deprecated and shouldn= 't be > + used. > memory.swappiness set/show swappiness parameter of vms= can > (See sysctl's vm.swappiness) > memory.move_charge_at_immigrate set/show controls of moving charges > @@ -898,8 +900,10 @@ At reading, current status of OOM is shown. > The number of processes belonging to this cgroup killed by any > kind of OOM killer. > > -11. Memory Pressure > -=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D > +11. Memory Pressure (DEPRECATED) > +=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D= =3D=3D=3D=3D=3D=3D=3D=3D > + > +THIS IS DEPRECATED! > > The pressure level notifications can be used to monitor the memory > allocation cost; based on the pressure, applications can implement > diff --git a/mm/memcontrol-v1.c b/mm/memcontrol-v1.c > index 07343e338e4e..420c7d15f12a 100644 > --- a/mm/memcontrol-v1.c > +++ b/mm/memcontrol-v1.c > @@ -1913,6 +1913,9 @@ static ssize_t memcg_write_event_control(struct ker= nfs_open_file *of, > event->register_event =3D mem_cgroup_oom_register_event; > event->unregister_event =3D mem_cgroup_oom_unregister_eve= nt; > } else if (!strcmp(name, "memory.pressure_level")) { > + pr_warn_once("pressure_level is deprecated and will be re= moved. " > + "Please report your usecase to linux-mm-@kva= ck.org " > + "if you depend on this functionality. \n"; Missing close paren? Extra space at the end too. > event->register_event =3D vmpressure_register_event; > event->unregister_event =3D vmpressure_unregister_event; > } else if (!strcmp(name, "memory.memsw.usage_in_bytes")) { > -- > 2.43.5 > >