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Sun, 16 Aug 2026 21:52:27 -0700 (PDT) From: Joshua Hahn To: Gregory Price Cc: Rakie Kim , akpm@linux-foundation.org, linux-mm@kvack.org, linux-kernel@vger.kernel.org, linux-cxl@vger.kernel.org, nvdimm@lists.linux.dev, ziy@nvidia.com, matthew.brost@intel.com, joshua.hahnjy@gmail.com, byungchul@sk.com, ying.huang@linux.alibaba.com, apopple@nvidia.com, david@kernel.org, ljs@kernel.org, liam@infradead.org, vbabka@kernel.org, rppt@kernel.org, surenb@google.com, mhocko@suse.com, dave@stgolabs.net, jic23@kernel.org, dave.jiang@intel.com, alison.schofield@intel.com, vishal.l.verma@intel.com, ira.weiny@intel.com, harry@kernel.org, kernel_team@skhynix.com, honggyu.kim@sk.com, yunjeong.mun@sk.com Subject: Re: [PATCH 0/4] mm/mempolicy: introduce package-aware weighted interleave Date: Sun, 16 Aug 2026 21:52:24 -0700 Message-ID: <20260817045225.1807518-1-joshua.hahnjy@gmail.com> X-Mailer: git-send-email 2.53.0 In-Reply-To: References: MIME-Version: 1.0 Content-Transfer-Encoding: 8bit X-Rspam-User: X-Stat-Signature: hm14tzjk7f8yoimrwdsrry6k3b8yywwy X-Rspamd-Server: rspam08 X-Rspamd-Queue-Id: 4E3A1180008 X-HE-Tag: 1786942349-680488 X-HE-Meta: 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 STooHW0l Z6TbDuowEAbabI2NJyyM8p8EmdHrnath6HIVW58QLe4Cq7lpvKa2a95Cu6/obyEYcUSdKj/O6024BHLLnrfapA9/5b1bgt2cNMlwGJTZn6UjDl4anZyeIHBwETh4z6yiZKBpv7QJXl5upFJU5OahRk8g5lklkySy8reFYwW0gmOw/VeQfSsK0dDFT8kv+oNwBStOnp/ejnwgf8JKhZnSfxx1QTnwdfWQWvDNesGiUe/eQe+Q54dzmoQFt3QYcI7zOzZk0Gpo4iVU2wbbeYELDAectm+wHyS/L6Ub+YkTEmTjWhne78ubQOxBrDGMv6bmmPrBoXxdxOtfZZ0BACwMHhCbpsC/5X+xSXn1evBXlQViJOX1hrAc3yMiVNYlTCG0eS+/n1UXBIYnWUDV1UMFVErGYeVV/Honxq1TmIXbQOX9ia731Dzlje/pwuyHlRGoAfHU+BTcfcYFOj+00WHac0buUjd0+HB0CnXNE4q9aPH0dtoezJJ/NFX4bisjTsnPtzTg/tiCaMEdNOqQ2o70LrZNZInDtxshDIPlx/pUz05n6xElauRCNc257uvjnBhXsDYFHNi2VaPvMgbJYBiHE6VcXy9Sl5x/iy0wAuk+VPAvtJxU= Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: List-Subscribe: List-Unsubscribe: On Sun, 16 Aug 2026 20:46:16 -0400 Gregory Price wrote: > On Thu, Aug 13, 2026 at 03:23:48PM +0900, Rakie Kim wrote: > > On Wed, 12 Aug 2026 22:37:06 -0400 Gregory Price wrote: > > > > The cpuset.mems = 0,2 you describe is the node set of package 0, so > > the tasks in that cgroup use node0 and node2 wherever they run. > > > > I think you are over-complicating the explanation and that's making it > hard for folks to reason about this. > > My best understanding here is for multi-socket systems, weighted > interleave as-designed is inherently sub-optimal for scaled workloads > that utilize multi-socket ("package") memory resources (DRAM, CXL...) I was thinking about this and I think Gregory is right here. I wonder how much of the framing around this series can be preserved / simplified if we just say "prevent tasks from allocating memory cross-socket". I also wonder if instead of limiting this to weighted interleave, this can sit on top of other mpols and just nodemasks against cross-socket nodes. > I think there is also an assumption that total memory utilization is > less than the total capacity - otherwise some of the assumptions here > break, but that comes with the general weighted interleave story. > > I'm getting back from vacation, I will take a closer look this week. I am also out on vacation this week : -) I'll take a closer look along with the code next week as well. Thanks, Rakie and Gregory! Joshua