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Miller" , Jakub Kicinski , Simon Horman , Vlastimil Babka , Suren Baghdasaryan , Michal Hocko , Brendan Jackman , Johannes Weiner , Zi Yan , Yunsheng Lin , Huacai Zhou Content-Type: text/plain; charset="UTF-8" Content-Transfer-Encoding: quoted-printable X-Rspamd-Queue-Id: 0F93C180008 X-Rspamd-Server: rspam11 X-Rspam-User: X-Stat-Signature: tt1fw8gjktxb15btsbnsogs814fp6zgn X-HE-Tag: 1760438359-340366 X-HE-Meta: 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 s1S1MeCR 0fy8cMZLIp2fcMoQY8DI46Of3pGfy3DUaHvbb7EB5BjRZnSZ8hIGy6Oj/XQEMXdYnNO2JOG6Ab9tEXNZngZ9NlIgTEAMUxKmK8tGiyFVnqIVxj4HaxwtIzt7Okvai6w58B4vefwVWNx1t4fGYTxNx/Jl5BTuPaYxl8ua1ERylyCP+Zrv9VyBZaQlctezhKw3XDKisD6EJBt9vp2ipCo2dyXsd7GDCy1vwq3DTvSinub1DgqO8O+gRvGRdN9+zf9lPwWKcg80MKmZV0t8= 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, Oct 14, 2025 at 3:19=E2=80=AFAM Barry Song <21cnbao@gmail.com> wrot= e: > > > > > > > > > > > > I think you are missing something to control how much memory can b= e > > > > pushed on each TCP socket ? > > > > > > > > What is tcp_wmem on your phones ? What about tcp_mem ? > > > > > > > > Have you looked at /proc/sys/net/ipv4/tcp_notsent_lowat > > > > > > # cat /proc/sys/net/ipv4/tcp_wmem > > > 524288 1048576 6710886 > > > > Ouch. That is insane tcp_wmem[0] . > > > > Please stick to 4096, or risk OOM of various sorts. > > > > > > > > # cat /proc/sys/net/ipv4/tcp_notsent_lowat > > > 4294967295 > > > > > > Any thoughts on these settings? > > > > Please look at > > https://www.kernel.org/doc/Documentation/networking/ip-sysctl.txt > > > > tcp_notsent_lowat - UNSIGNED INTEGER > > A TCP socket can control the amount of unsent bytes in its write queue, > > thanks to TCP_NOTSENT_LOWAT socket option. poll()/select()/epoll() > > reports POLLOUT events if the amount of unsent bytes is below a per > > socket value, and if the write queue is not full. sendmsg() will > > also not add new buffers if the limit is hit. > > > > This global variable controls the amount of unsent data for > > sockets not using TCP_NOTSENT_LOWAT. For these sockets, a change > > to the global variable has immediate effect. > > > > > > Setting this sysctl to 2MB can effectively reduce the amount of memory > > in TCP write queues by 66 %, > > or allow you to increase tcp_wmem[2] so that only flows needing big > > BDP can get it. > > We obtained these settings from our hardware vendors. Tell them they are wrong. > > It might be worth exploring these settings further, but I can=E2=80=99t q= uite see > their connection to high-order allocations, since high-order allocations = are > kernel macros. > > #define SKB_FRAG_PAGE_ORDER get_order(32768) > #define PAGE_FRAG_CACHE_MAX_SIZE __ALIGN_MASK(32768, ~PAGE_MASK) > #define PAGE_FRAG_CACHE_MAX_ORDER get_order(PAGE_FRAG_CACHE_MAX_SIZ= E) > > Is there anything I=E2=80=99m missing? What is your question exactly ? You read these macros just fine. What is your point ? We had in the past something dynamic that we removed commit d9b2938aabf757da2d40153489b251d4fc3fdd18 Author: Eric Dumazet Date: Wed Aug 27 20:49:34 2014 -0700 net: attempt a single high order allocation