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[173.79.56.208]) by smtp.gmail.com with ESMTPSA id d75a77b69052e-47183bc479fsm22813441cf.17.2025.02.10.07.47.59 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Mon, 10 Feb 2025 07:47:59 -0800 (PST) Date: Mon, 10 Feb 2025 10:47:58 -0500 From: Gregory Price To: Byungchul Park Cc: "Harry (Hyeonggon) Yoo" <42.hyeyoo@gmail.com>, Honggyu Kim , kernel_team@skhynix.com, Matthew Wilcox , lsf-pc@lists.linux-foundation.org, linux-mm@kvack.org, linux-cxl@vger.kernel.org Subject: Re: [LSF/MM/BPF TOPIC] Restricting or migrating unmovable kernel allocations from slow tier Message-ID: References: <20250207072024.GA48419@system.software.com> <20250210071741.GB39454@system.software.com> Precedence: bulk X-Mailing-List: linux-cxl@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20250210071741.GB39454@system.software.com> On Mon, Feb 10, 2025 at 04:17:41PM +0900, Byungchul Park wrote: > On Mon, Feb 10, 2025 at 01:00:02AM -0500, Gregory Price wrote: > > > > You can probably actually (maybe?) collect data on this today - but > > you still have to contend with #2 and #3. > > Ah. You seem to mean those works should be serialized. Right? If it > should be for some reason, then it could be sensible. > I'm suggesting that there isn't a strong reason (yet) to consider such a complicated change. As Willy has said, it's a fairly fundamental change for a single-reason (CXL), which does not bode well for its acceptance. Honestly trying to save you some frustration. It would behoove you to find stronger reasons (w/ data) or consider different solutions. Right now there are stronger, simplers solutions to the ZONE_NORMAL capacity issue (struct page resize, huge pages) for possible capacities. I also think someone should actively ask whether `struct page` can be hosted on remote memory without performance loss. I may look into this. ~Gregory