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[173.79.56.208]) by smtp.gmail.com with ESMTPSA id 6a1803df08f44-6e8f715b475sm57816386d6.75.2025.03.10.07.13.59 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Mon, 10 Mar 2025 07:14:00 -0700 (PDT) Date: Mon, 10 Mar 2025 10:13:58 -0400 From: Gregory Price To: Rakie Kim Cc: akpm@linux-foundation.org, linux-mm@kvack.org, linux-kernel@vger.kernel.org, linux-cxl@vger.kernel.org, joshua.hahnjy@gmail.com, dan.j.williams@intel.com, ying.huang@linux.alibaba.com, kernel_team@skhynix.com, honggyu.kim@sk.com, yunjeong.mun@sk.com Subject: Re: [PATCH 0/4] mm/mempolicy: Add memory hotplug support in weighted interleave Message-ID: References: <20250310090407.631-1-rakie.kim@sk.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20250310090407.631-1-rakie.kim@sk.com> X-Stat-Signature: r8fjnm5uyjse67qdqx3ae4uinbf6jthw X-Rspam-User: X-Rspamd-Queue-Id: 71451C001C X-Rspamd-Server: rspam04 X-HE-Tag: 1741616041-80468 X-HE-Meta: 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 ZTiNHeUf 2LH5CjJzEYmvrYWUEMLLWjmM7hi2IcIgIqvUjNjAeUQYzCMfPB/Foy0XNIE+zGe3hXh1XsVJlJbdqKVD7MPpoqfelk6NLqNCI4e34xcSj5LPBw7TP0H1N1hjZQcRZ4qPqw5c7VWXto01CYQAGxuo+IQxKLdiqChySTRdqINXhNewHxgN6WmfMCVYKbu3kGorfOjULjAUvJolCQ2owTpeiC9WwNEv4e/nAPDuuku8IQOLL3CJm+9mtYJy4KwIEM4HjBjUNiLNjwo9CWCofXYOgWlo4Ru+69Sx88Tnl2Qu0+SlO7+WqyYif/aT9zqeYLL4GbPtqL4jZ2WA059nKuVQEE7eGMwUUeqlge1pQKo0WPuNyd1ZnzDs7M9EPbWy4KINH/dUSDqlDOkqwbXOgRUKXfIqZ1T7loxgn0htILzbkhT+ClTpc6QRceKAqlkD4uX2rclWKmPrb/BRrgOsObPkn4eDMh+WVPomBLbYk X-Bogosity: Ham, tests=bogofilter, spamicity=0.000203, version=1.2.4 Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: List-Subscribe: List-Unsubscribe: On Mon, Mar 10, 2025 at 06:03:59PM +0900, Rakie Kim wrote: > On Fri, 7 Mar 2025 16:55:40 -0500 Gregory Price wrote: > > On Fri, Mar 07, 2025 at 10:56:04AM -0500, Gregory Price wrote: > > > > > > I think the underlying issue you're dealing with is that the system is > > > creating more nodes for you than it should. > > > > > > > Looking into this for other reasons, I think you are right that multiple > > numa nodes can exist that cover the same memory - just different > > regions. > > > > I understand your concerns, and I agree that the most critical issue at the > moment is that the system is generating more nodes than necessary. > We need to conduct a more thorough analysis of this problem, but a detailed > investigation will require a significant amount of time. In this context, > these patches might offer a quick solution to address the issue. > I dug into the expected CEDT / CFMWS behaviors and had some discussions with Dan and Jonathan - assuming your CEDT has multiple CFMWS to cover the same set of devices, this is the expected behavior. https://lore.kernel.org/linux-mm/Z226PG9t-Ih7fJDL@gourry-fedora-PF4VCD3F/T/#m2780e47df7f0962a79182502afc99843bb046205 Basically your BIOS is likely creating one per device and likely one per host bridge (to allow intra-host-bridge interleave). This puts us in an awkward state, and I need some time to consider whether we should expose N_POSSIBLE nodes or N_MEMORY nodes. Probably it makes sense to expose N_MEMORY nodes and allow for hidden state, as the annoying corner condition of a DCD coming and going most likely means a user wouldn't be using weighted interleave anyway. So if you can confirm what you CEDT says compared to the notes above, I think we can move forward with this. ~Gregory