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[96.255.20.138]) by smtp.gmail.com with ESMTPSA id af79cd13be357-8cda1fe19d3sm1245799585a.19.2026.03.16.12.45.25 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Mon, 16 Mar 2026 12:45:26 -0700 (PDT) Date: Mon, 16 Mar 2026 15:45:24 -0400 From: Gregory Price To: Joshua Hahn Cc: Rakie Kim , akpm@linux-foundation.org, linux-mm@kvack.org, linux-kernel@vger.kernel.org, linux-cxl@vger.kernel.org, ziy@nvidia.com, matthew.brost@intel.com, byungchul@sk.com, ying.huang@linux.alibaba.com, apopple@nvidia.com, david@kernel.org, lorenzo.stoakes@oracle.com, Liam.Howlett@oracle.com, vbabka@suse.cz, rppt@kernel.org, surenb@google.com, mhocko@suse.com, dave@stgolabs.net, jonathan.cameron@huawei.com, dave.jiang@intel.com, alison.schofield@intel.com, vishal.l.verma@intel.com, ira.weiny@intel.com, dan.j.williams@intel.com, kernel_team@skhynix.com, honggyu.kim@sk.com, yunjeong.mun@sk.com Subject: Re: [LSF/MM/BPF TOPIC] [RFC PATCH 0/4] mm/mempolicy: introduce socket-aware weighted interleave Message-ID: References: <20260316051258.246-1-rakie.kim@sk.com> <20260316151933.3093626-1-joshua.hahnjy@gmail.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20260316151933.3093626-1-joshua.hahnjy@gmail.com> X-Rspamd-Server: rspam01 X-Rspamd-Queue-Id: 286A114000E X-Stat-Signature: q3ga6pxghahzdzthtf5z4wzfxnmauq1f X-Rspam-User: X-HE-Tag: 1773690328-899294 X-HE-Meta: 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 kILXAyrN 65dRg84K/h2FlcfMhyVcgZqAT7jkV+LtkdkJYgvcvc9Mzl+PXPAY0XMIAbRf59cEa5wobmJruu+TOh9MTL6qVR3wYfsw6wSrARTQc Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: List-Subscribe: List-Unsubscribe: On Mon, Mar 16, 2026 at 08:19:32AM -0700, Joshua Hahn wrote: > > In that sense I thought the word "prefer" was a bit confusing, since I > thought it would mean that it would try to fulfill the alloactions > from within a packet first, then fall back to remote packets if that > failed. (Or maybe I am just misunderstanding your explanation. Please > do let me know if that is the case : -) ) > > If what I understand is the case , I think this is the same thing as > just restricting allocations to be socket-local. I also wonder if > this idea applies to other mempolicies as well (i.e. unweighted interleave) > I was thinking about this as well, and in my head i think you have to consider a 2x2 situation cpuset | multi-socket-cpu single-socket-cpu ================================================================== single-socket-mem | mem-package mem-package ------------------------------------------------------------------ multi-socket-mem | global global ------------------------------------------------------------------ But I think this reduces to cpuset nodes dictates the weights used - which should already be the case with the existing code. I think you are right that we need to be very explicit about the fallback semantics here - but that may just be a matter of dictating whether the allocation falls back or prefers direct reclaim to push pages out of their requested nodes. ~Gregory