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AJvYcCXoqIad5qkFqxUPv99duYvzSY7GaIZk7AIbwmNNaxy7exMvBjGlwXq6LgCao/qnTcVAUGtYzlRlpQ==@kvack.org X-Gm-Message-State: AOJu0Ywr6jvpW2ERm+FoQTWRmv/x1UBUhKJFWv+QfHn3FM6wBnbLCQxn RAh19qyERZyd1IWZWwVbIod5Oq/K9Ek1qS6Gc0rCjxCg2BxHu/EAQVa4bMignVoRYdjGUskzbyD /sanllD4pkshUvBXF4NppNpqlnPrnV3yyc6kww9BN X-Gm-Gg: ASbGnctrsMYmltqLWP8dUxqtsvEYekBYaUttlaWQie4D0o5if3OKSlGjtnpkLdSeb+/ B/+ctokdsNEcYwW8IJFa/zv/E3kVqze4/D/dPP1bVZSWIo6Hxfvv28nK3MNpI0vdSVZfV4rxlzU Fl5+PRHamkDXlpSNH5YjOqpQrJ3DgoM71SGL4Ju7Qq3iOU80rmxBdt9W03gp9Pg+Xb+3cNIk1k2 wX/UMNzAfHfNVipv84aqkk4o/ytjgd5cpIKSKkqz2wLC+WU X-Google-Smtp-Source: AGHT+IEg4W97E07D/JlFeehtaiwxPWUF4AnFa19XV+i75fU3XCe4tqE6HcJMrlHWpbyEhBQz5BtcSmGxO+C8g2IB2zw= X-Received: by 2002:a17:90b:388b:b0:312:ec:412f with SMTP id 98e67ed59e1d1-31e506ef9afmr612863a91.14.1753210190763; Tue, 22 Jul 2025 11:49:50 -0700 (PDT) MIME-Version: 1.0 References: <20250722071146.48616-1-daniel.sedlak@cdn77.com> <3db01bc9-f6ea-41f7-8cbf-fb33e522694a@redhat.com> In-Reply-To: <3db01bc9-f6ea-41f7-8cbf-fb33e522694a@redhat.com> From: Kuniyuki Iwashima Date: Tue, 22 Jul 2025 11:49:39 -0700 X-Gm-Features: Ac12FXyhexe6ErD4K44AhQAu2qUuwklTJsSiRV2SdD5og77T3xQkMML2F4JwTjY Message-ID: Subject: Re: [PATCH v3] memcg: expose socket memory pressure in a cgroup To: Waiman Long Cc: Shakeel Butt , =?UTF-8?Q?Michal_Koutn=C3=BD?= , Daniel Sedlak , "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 , Roman Gushchin , Muchun Song , cgroups@vger.kernel.org, Matyas Hurtik Content-Type: text/plain; charset="UTF-8" Content-Transfer-Encoding: quoted-printable X-Rspamd-Server: rspam12 X-Rspamd-Queue-Id: 2D348A0009 X-Stat-Signature: 85mu5z6icjhgkgzn3956kfy697c74oy8 X-Rspam-User: X-HE-Tag: 1753210191-336561 X-HE-Meta: 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 /OFoaPju lYGIOzRzsc0Bf1HClSeD5+oD6pZI64YVVTR1KjvghadDbIxtvm3m010ZmxU2FQvJF9v5yAr820ee8e0OFhyk62rFErIJ77p+fPaWloAwEhkw6zmOOdhBWVK3jJ78ZOe4ABYJU1xpmFoW2atZDG3g4oi3plr/99J914Ai6oiHeMyJcAmzWub8585A1u6m+2DX0ENLBs66Cg2JtA1dvwZUq3jVYkdnpawJKF8Qm7FIK9biqjmEuEfX+mmli5ODTUgTUsWojRTBkBySM/TJg3jiGYbctcO5I1KnIybLGaUpPFnTek5Zy5/2PbfpNNs4qhYu22aKH3us0LSm0uU20/NOxraQE1g== 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 Tue, Jul 22, 2025 at 11:41=E2=80=AFAM Waiman Long wro= te: > > > On 7/22/25 2:27 PM, Kuniyuki Iwashima wrote: > > On Tue, Jul 22, 2025 at 10:50=E2=80=AFAM Shakeel Butt wrote: > >> On Tue, Jul 22, 2025 at 10:57:31AM +0200, Michal Koutn=C3=BD wrote: > >>> Hello Daniel. > >>> > >>> On Tue, Jul 22, 2025 at 09:11:46AM +0200, Daniel Sedlak wrote: > >>>> /sys/fs/cgroup/**//memory.net.socket_pressure > >>>> > >>>> The output value is an integer matching the internal semantics of th= e > >>>> struct mem_cgroup for socket_pressure. It is a periodic re-arm clock= , > >>>> representing the end of the said socket memory pressure, and once th= e > >>>> clock is re-armed it is set to jiffies + HZ. > >>> I don't find it ideal to expose this value in its raw form that is > >>> rather an implementation detail. > >>> > >>> IIUC, the information is possibly valid only during one jiffy interva= l. > >>> How would be the userspace consuming this? > >>> > >>> I'd consider exposing this as a cummulative counter in memory.stat fo= r > >>> simplicity (or possibly cummulative time spent in the pressure > >>> condition). > >>> > >>> Shakeel, how useful is this vmpressure per-cgroup tracking nowadays? = I > >>> thought it's kind of legacy. > >> > >> Yes vmpressure is legacy and we should not expose raw underlying numbe= r > >> to the userspace. How about just 0 or 1 and use > >> mem_cgroup_under_socket_pressure() underlying? In future if we change > >> the underlying implementation, the output of this interface should be > >> consistent. > > But this is available only for 1 second, and it will not be useful > > except for live debugging ? > > If the new interface is used mainly for debugging purpose, I will > suggest adding the CFTYPE_DEBUG flag so that it will only show up when > "cgroup_debug" is specified in the kernel command line. Sorry, I meant the signal that is available only for 1 second does not help troubleshooting and we cannot get any hint from 0 _after_ something bad happens. The flag works if the issue is more consistent or can be reproduced and we can reboot, but it does not fit here. I guess the flag is for a different use case ?