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Sun, 22 Dec 2024 15:21:33 +0800 From: "Huang, Ying" To: Hyeonggon Yoo Cc: Joshua Hahn , "gourry@gourry.net" , kernel_team@skhynix.com, 42.hyeyoo@gmail.com, "rafael@kernel.org" , "lenb@kernel.org" , "gregkh@linuxfoundation.org" , "akpm@linux-foundation.org" , Honggyu Kim , Rakie Kim , "dan.j.williams@intel.com" , "Jonathan.Cameron@huawei.com" , "dave.jiang@intel.com" , "horen.chuang@linux.dev" , "hannes@cmpxchg.org" , "linux-mm@kvack.org" , "linux-kernel@vger.kernel.org" , "linux-acpi@vger.kernel.org" , "kernel-team@meta.com" Subject: Re: [External Mail] [RFC PATCH v2] Weighted interleave auto-tuning In-Reply-To: <3682b9cf-213c-497d-ab81-f70e1a785716@sk.com> (Hyeonggon Yoo's message of "Fri, 20 Dec 2024 17:25:28 +0900") References: <20241219191845.3506370-1-joshua.hahnjy@gmail.com> <3682b9cf-213c-497d-ab81-f70e1a785716@sk.com> Date: Sun, 22 Dec 2024 15:21:32 +0800 Message-ID: <87r060i3nn.fsf@DESKTOP-5N7EMDA> User-Agent: Gnus/5.13 (Gnus v5.13) MIME-Version: 1.0 Content-Type: text/plain; charset=ascii X-Stat-Signature: 9ha3hddftca84u5xo7jx33k5c1771mgh X-Rspam-User: X-Rspamd-Queue-Id: 323EE140008 X-Rspamd-Server: rspam08 X-HE-Tag: 1734852072-446278 X-HE-Meta: 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 xIWG32a3 TjvfOhXEqRm1yNqKAl5LdFRAIZIR+3CNbXu9eu5CgpmxeCSrTyb7oEyf04/ueNjuxa/FWAmO5Gu5QrPJ+jlWt9gqhF5V7z4yfsjyvb+TvsanYfx+Y258lyPuWTFkHgBADuUA1mpRau3M6xvlAjXRHV38KGJfUSoqBfIRtehyGODeXPCM/f33SXMnghUg0U3RHS0EXryCUyzybBBacm3qjWydvIDyuoo+vRQYj0YajvGC9gd4BWeqUE0B9E0zmBRw9KBrNLHvs+GVwyD08SP2JcnTMt7eByL1H/K5wRRO/leGXq1gh58SD0NkMeNxdF+YtSTbn3IGEeFyfsdR9jvA3O+y2VkBWJNUEiikh9+4RCiRowbL1WFaGjJh/3Q3oF5wY3Kz8 X-Bogosity: Ham, tests=bogofilter, spamicity=0.000000, version=1.2.4 Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: List-Subscribe: List-Unsubscribe: Hyeonggon Yoo writes: > On 2024-12-20 4:18 AM, Joshua Hahn wrote: [snip] > > By the way, this might be out of scope, but let me ask for my own > learning. > > We have a server with 2 sockets, each attached with local DRAM and CXL > memory (and thus 4 NUMA nodes). When accessing remote socket's memory > (either CXL or not), the bandwidth is limited by the interconnect's > bandwidth. > > On this server, ideally weighted interleaving should be configured > within a socket (e.g. local NUMA node + local CXL node) because > weighted interleaving does not consider the bandwidth when accessed > from a remote socket. If multiple sockets are considered, what is the best behavior? The process may be cross-socket too. So, we will need to use set_mempolicy() to bind tasks to sockets firstly. Then, it may be better to use per-task weights. > So, the question is: On systems with multiple sockets (and CXL mem > attached to each socket), do you always assume the admin must bind to > a specific socket for optimal performance or is there any plan to > mitigate this problem without binding tasks to a socket? > [snip] --- Best Regards, Huang, Ying