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[173.79.60.52]) by smtp.gmail.com with ESMTPSA id 6a1803df08f44-91c10c0bd4csm51371086d6.30.2026.10.22.07.11.50 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Thu, 22 Oct 2026 07:11:51 -0700 (PDT) Date: Thu, 22 Oct 2026 10:11:49 -0400 From: Gregory Price To: Li Zhe Cc: akpm@linux-foundation.org, david@kernel.org, ziy@nvidia.com, joshua.hahnjy@gmail.com, rakie.kim@sk.com, ying.huang@linux.alibaba.com, ljs@kernel.org, mhocko@suse.com, muchun.song@linux.dev, roman.gushchin@linux.dev, shakeel.butt@linux.dev, weixugc@google.com, cgroups@vger.kernel.org, linux-doc@vger.kernel.org, linux-kernel@vger.kernel.org, linux-mm@kvack.org Subject: Re: [RFC 0/2] mm: add source selectors to memory.reclaim Message-ID: References: <20261019141401.11927-1-lizhe.67@bytedance.com> <30457046-a662-4ff7-a6a8-100398d7a806@bytedance.com> <179264138036.2549665.17429111144570830454.b4-reply@b4> <9b715272-3ed9-42da-a6ae-467e8ae00c0b@bytedance.com> X-Archived-By: MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <9b715272-3ed9-42da-a6ae-467e8ae00c0b@bytedance.com> X-Rspamd-Queue-Id: A78664000A X-Stat-Signature: jgd5xc9o66kztjd3atusgdo7ttxxhbio X-Rspamd-Server: rspam06 X-Spam-Status: No, score=-5.8 required=3.0 tests=BAYES_00,DKIM_SIGNED, DKIM_VALID,DKIM_VALID_AU,HEADER_FROM_DIFFERENT_DOMAINS, MAILING_LIST_MULTI,SPF_HELO_PASS,SPF_PASS autolearn=no autolearn_force=no version=4.0.1 X-Rspam-User: X-HE-Tag: 1792678312-800017 X-HE-Meta: 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 HcXMEdzw D8DUnhTxdDo4HIKx2Xzdj9s82YWiskZF6uKqT3GN2qeT13NU54f3hcTmIi73I9AwJYM9r+mUwkS+KaFIr8hd/8aIvApK5J60ucwTnJxM/dz7RwbwBn6uyxQmxJfzbv0uFNwbArMboWXklnDal4QkqgINqy+KYXaX0lICkwYUqSXm+3uiLQgU5yNw0ghDXNCXeYMuRNMOdkCS85tFqqvgHxUCWBuHkJ9CGXnhHAcFCFnfh38vxCeBUQrjm+srRCb8W0Z5J5DzxUHeM+0WQhAeYnrOXYwFkKTAZvgHOqX7UefbjOfj7P/IoQdRjzaB3Lg4Y33HwkFoc9/Rz3YkY0wnR/pbB3QVYRT9MOKBw+UDywz2gKdB2kh2Bo79BRFEJ5EefboJctCFFC19gRNAzbnN+tPxLVA== Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: List-Subscribe: X-Spam-Checker-Version: SpamAssassin 4.0.1 (2024-03-26) on aws-us-west-2-korg-listserv-alma10-1 On Thu, Oct 22, 2026 at 05:43:49PM +0800, Li Zhe wrote: > On 10/22/26 11:56 AM, Gregory Price (Meta) wrote: > > So userspace cannot rely on one write to memory.reclaim to produce a > final per-node distribution. The intended usage is a feedback loop: the > controller observes the memcg's resident distribution, chooses the source > nodes it wants to relieve, applies source-scoped reclaim pressure, > observes the new distribution, and iterates. > I think the critical question is what CAN userspace rely on? We can make a bunch of feedback loop interfaces, but there's no guarantee they'll actually be useful. > > > > At the very least i think you need to add details in your cover that > > demonstrates the process of doing something like per-node resident > > ratios, and show that it works as you intend. > > Agreed. I will update the cover letter to make this model clearer. I > will also make clear that source=nodes is not a final net per-node > footprint guarantee and does not change memory.reclaim completion > accounting. > To be clear, I think not just making it clearer, but if you can show some tests that demonstrate the reliable behavior of the interface extension under different scenarios - that would be compelling. ~Gregory