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b=i1zGF7/sXDGh16efrnNHdWmhZTD0x2pFwIZOavKSuFz2N2xtPiz89vS+Sy1zhba7b FEnT9pU71iW1MyZNNXcGc+cGkz+XnfIw0RzpAiskj7GY1Gg75WAsOQ82daAXmiW+Cc aCbidToP7gn37uvs/LYVIM08JTBfpfHPMoaPEVSs= Date: Mon, 6 Apr 2026 12:16:01 -0700 From: Andrew Morton To: "JP Kobryn (Meta)" Cc: linux-mm@kvack.org, willy@infradead.org, hannes@cmpxchg.org, david@kernel.org, ljs@kernel.org, Liam.Howlett@oracle.com, vbabka@kernel.org, rppt@kernel.org, surenb@google.com, mhocko@suse.com, kasong@tencent.com, qi.zheng@linux.dev, shakeel.butt@linux.dev, baohua@kernel.org, axelrasmussen@google.com, yuanchu@google.com, weixugc@google.com, riel@surriel.com, kuba@kernel.org, edumazet@google.com, netdev@vger.kernel.org, linux-kernel@vger.kernel.org, kernel-team@meta.com Subject: Re: [PATCH v3] mm/vmpressure: skip socket pressure for costly order reclaim Message-Id: <20260406121601.0f4f3a6886098371e40d6711@linux-foundation.org> In-Reply-To: <6a41259c-bf69-49d5-9cba-80a5feb8ee8a@linux.dev> References: <20260406174425.61692-1-jp.kobryn@linux.dev> <20260406105417.28fda9587146a011af2fb876@linux-foundation.org> <6a41259c-bf69-49d5-9cba-80a5feb8ee8a@linux.dev> X-Mailer: Sylpheed 3.7.0 (GTK+ 2.24.33; x86_64-pc-linux-gnu) Mime-Version: 1.0 Content-Type: text/plain; charset=US-ASCII Content-Transfer-Encoding: 7bit X-Rspamd-Queue-Id: A8B32C0007 X-Stat-Signature: k86e335tqzcawb4xqe7q4m3adhqasm35 X-Rspam-User: X-Rspamd-Server: rspam07 X-HE-Tag: 1775502964-754166 X-HE-Meta: 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 4dM1HdpY i4U4rc4Sx+LXMKyl0E7fdEGPWn3K+U57TRCegF2jv7YvoHWARPRDXmxMeJ/d2LAbJx39zDi+ftQ/sma0sZEWUP3A3jpk28uaOpnXsEHLwK8BQ4YKwphMaCqFVbHf+JvB8PZt2u0wZ+5MEcF82DIMJU46M1WZJRbkI2F8EoG1PGh6xo/ygXZhwLgJ+70wIVIhzG2ydPYEnkXElKrBM4j9OHyjRMSzR27rpgy2bqhP1bhKPyKS1R42xxz7+R2wwJYJX+L7t Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: List-Subscribe: List-Unsubscribe: On Mon, 6 Apr 2026 12:07:57 -0700 "JP Kobryn (Meta)" wrote: > Let me know if this data helps, and if you'd like this added to the > changelog. > > On one affected host with impacted net throughput, the memory state at > the time showed ~15GB available, zero cgroup pressure, and the following > buddyinfo state: > > Order FreePages > 0: 133,970 > 1: 29,230 > 2: 17,351 > 3: 18,984 > 7+: 0 > > Using bpf, it was found that 94% of vmpressure calls on this host were > from order-7 kswapd reclaim. > > TCP minimum recv window is rcv_ssthresh:19712. > > Before patch: > 723 out of 3,843 (19%) TCP connections stuck at minimum recv window > > After live-patching and ~30min elapsed: > 0 out of 3,470 TCP connections stuck at minimum recv window Well I'm impressed ;) Yes please, it's a useful thing to include. When people look at a contribution, question #1 is "why should I spend time on this". A clear (and tasty) description of userspace benefit is the ideal way of answering that.