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AJvYcCWyKoC+kpsf+/HnyN2sW/xlCX9pgoRknC9jXlRmAOPS/cEYu0MT3qUpUbalLPBeZAnDPlyo2JMIEA==@kvack.org X-Gm-Message-State: AOJu0YzGVwV2bHiiL5/XWbM5HrZv+pLgOK97WH7/38B7htQfCcV9GILZ 8CEKNydMu1TvDK8s5K44JTtsxPdYLOMvPgfN9ywyhCdQCrnaLijz0WF0CSoPApjgGRo7QEG2Cyp if3cWdBInCxnXqXPIB33BskMAsblHrFJSLYhDR56u X-Gm-Gg: ASbGncs035rabsargEXG8pphh22sY9DG9819GBI1JJ/pd0urufC4FcjnnGvollTJ+f7 UkHvH+4uGBfUVoWJq5488m3C//EMB6kd8c7giAaRrJwHUi4AiCkkC77wc7UGeaTAPDg2KX023CQ zNl8b77CwtiUhJjn/ny7MGd5p5QacNlVzbNjSVyBHU0718ppgVLjdbkFmAk6Om+0VZNZTnNl6Eu rZnaeg2coN+rCNIo4E/KyfTM8xFDDZ1bAMyAlnuZPnmidQeD5ex0dtoK/XF1Rc46/aB2jfF7g== X-Google-Smtp-Source: AGHT+IFXcR4/a/uWu2/COMG2rM2MXmYSeyVnHJVJ071uBYQhdmJ2s12d0Sglrmv8RLNynXPyIpu3cpFeni0ANJye8G0= X-Received: by 2002:aa7:df92:0:b0:637:d2d6:dddd with SMTP id 4fb4d7f45d1cf-639d5c6f393mr19995045a12.36.1760554716460; Wed, 15 Oct 2025 11:58:36 -0700 (PDT) MIME-Version: 1.0 References: <87qzvdqkyh.fsf@linux.dev> <13b5aeb6-ee0a-4b5b-a33a-e1d1d6f7f60e@cdn77.com> <87o6qgnl9w.fsf@linux.dev> <87a5205544.fsf@linux.dev> <875xcn526v.fsf@linux.dev> <89618dcb-7fe3-4f15-931b-17929287c323@cdn77.com> <6ras4hgv32qkkbh6e6btnnwfh2xnpmoftanw4xlbfrekhskpkk@frz4uyuh64eq> In-Reply-To: From: Kuniyuki Iwashima Date: Wed, 15 Oct 2025 11:58:23 -0700 X-Gm-Features: AS18NWCCDR5AqbojOF4FmdytvEGOhlifSaI5ISfKVV9sd4073qOpkYTl1jQCD34 Message-ID: Subject: Re: [PATCH v5] memcg: expose socket memory pressure in a cgroup To: Shakeel Butt Cc: Daniel Sedlak , Roman Gushchin , "David S. Miller" , Eric Dumazet , Jakub Kicinski , Paolo Abeni , Simon Horman , Jonathan Corbet , Neal Cardwell , David Ahern , Andrew Morton , Yosry Ahmed , linux-mm@kvack.org, netdev@vger.kernel.org, Johannes Weiner , Michal Hocko , Muchun Song , cgroups@vger.kernel.org, Tejun Heo , =?UTF-8?Q?Michal_Koutn=C3=BD?= , Matyas Hurtik Content-Type: text/plain; charset="UTF-8" Content-Transfer-Encoding: quoted-printable X-Rspam-User: X-Stat-Signature: u466daas3ms14qyitkg54c6i384xuqot X-Rspamd-Queue-Id: 61A6B160012 X-Rspamd-Server: rspam09 X-HE-Tag: 1760554718-212351 X-HE-Meta: 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 /irb3paD 4kP5HJkflXSQxvMgNpdNFU1/QuOw9uMrYK5F4xLD5YoMqG5ZMTeMeSDBfo93ZRk1pdcrOhGBYmEgkeEeEnpVbc9loEWQaebH/caYaBv+u8VMLLjvH8O1sUy4nqiu5Bi1mWTU0AeM9chNMiioi4NIqYeePLtWJhLxTHjjuasbISPjfWVj+i+cI80splfV1P6LVNcow 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, Oct 15, 2025 at 11:39=E2=80=AFAM Shakeel Butt wrote: > > On Wed, Oct 15, 2025 at 11:21:17AM -0700, Kuniyuki Iwashima wrote: > > On Tue, Oct 14, 2025 at 1:33=E2=80=AFPM Shakeel Butt wrote: > > > > > > On Mon, Oct 13, 2025 at 04:30:53PM +0200, Daniel Sedlak wrote: > > > [...] > > > > > > > > How about we track the actions taken by the callers of > > > > > > > > mem_cgroup_sk_under_memory_pressure()? Basically if network= stack > > > > > > > > reduces the buffer size or whatever the other actions it ma= y take when > > > > > > > > mem_cgroup_sk_under_memory_pressure() returns, tracking tho= se actions > > > > > > > > is what I think is needed here, at least for the debugging = use-case. > > > > > > > > I am not against it, but I feel that conveying those tracked action= s (or how > > > > to represent them) to the user will be much harder. Are there alrea= dy > > > > existing APIs to push this information to the user? > > > > > > > > > > I discussed with Wei Wang and she suggested we should start tracking = the > > > calls to tcp_adjust_rcv_ssthresh() first. So, something like the > > > following. I would like feedback frm networking folks as well: > > > > I think we could simply put memcg_memory_event() in > > mem_cgroup_sk_under_memory_pressure() when it returns > > true. > > > > Other than tcp_adjust_rcv_ssthresh(), if tcp_under_memory_pressure() > > returns true, it indicates something bad will happen, failure to expand > > rcvbuf and sndbuf, need to prune out-of-order queue more aggressively, > > FIN deferred to a retransmitted packet. > > > > Also, we could cover mptcp and sctp too. > > > > I wanted to start simple and focus on one specific action but I am open > to other actins as well. Do we want a generic network throttled metric > or do we want different metric for different action? At the moment I > think for memcg, a single metric would be sufficient and then we can > have tracepoints for more fine grained debugging. I agree that a single metric would be enough if it can signal something bad is happening as a first step, then we can take further action with tracepoint, bpftrace, whatever.