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Tue, 03 Nov 2026 22:42:42 -0800 (PST) Received: from gourry-fedora-PF4VCD3F ([61.251.99.240]) by smtp.gmail.com with ESMTPSA id a92af1059eb24-1b245c57430sm5905073c88.18.2026.11.03.22.42.32 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Tue, 03 Nov 2026 22:42:41 -0800 (PST) Date: Wed, 4 Nov 2026 01:42:23 -0500 From: Gregory Price To: Li Zhe Cc: Tejun Heo , hannes@cmpxchg.org, mkoutny@suse.com, akpm@linux-foundation.org, david@kernel.org, ziy@nvidia.com, joshua.hahnjy@gmail.com, ying.huang@linux.alibaba.com, ljs@kernel.org, liam@infradead.org, rppt@kernel.org, surenb@google.com, mhocko@suse.com, cgroups@vger.kernel.org, linux-kernel@vger.kernel.org, linux-mm@kvack.org, bpf@vger.kernel.org Subject: Re: [PATCH 0/3] mm/mempolicy: add per-cgroup weighted interleave controls Message-ID: References: <20261103122816.48037-1-lizhe.67@bytedance.com> <0efbf4db1decd8e6bb6a5fcdcf897314@kernel.org> <03bceb67-d362-47a6-b555-ed5aa1f9bd3e@bytedance.com> X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Post: List-Help: List-Subscribe: List-Unsubscribe: List-Owner: Precedence: list MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <03bceb67-d362-47a6-b555-ed5aa1f9bd3e@bytedance.com> On Wed, Nov 04, 2026 at 10:44:46AM +0800, Li Zhe wrote: > > Does that distinction make the cgroup-scoped override acceptable? If not, > could you suggest a better way to support this kind of administrative > weight override without adding new mempolicy syscalls? > I'm a little confused why cgroup-anything is needed here when you could just override the weight table / interleave functions. I don't particularly like the idea of bpf hooks for a single mempolicy mode as opposed to something more generally useful - and I question how useful task-mempolicies are in general for tiered memory systems (they also affect kernel allocation placement, which is not great). You have many patch proposals recently trying to adjust the mempolicy components and I think it might be helpful if we could chat a bit about what big problems you're actually trying to solve. I get that you want better control over task/task-groups, i think that can be useful - but I also know that demotion immediately mucks all this placement logic up (and we can't check vma / task policies at demotion time) so I question how realisitic the value of these extensions will be. ~Gregory