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Received: from willy by casper.infradead.org with local (Exim 4.98.2 #2 (Red Hat Linux)) id 1uwMui-0000000BFcE-3PjP; Wed, 10 Sep 2025 15:39:16 +0000 Date: Wed, 10 Sep 2025 16:39:16 +0100 From: Matthew Wilcox To: Bharata B Rao Cc: linux-kernel@vger.kernel.org, linux-mm@kvack.org, Jonathan.Cameron@huawei.com, dave.hansen@intel.com, gourry@gourry.net, hannes@cmpxchg.org, mgorman@techsingularity.net, mingo@redhat.com, peterz@infradead.org, raghavendra.kt@amd.com, riel@surriel.com, rientjes@google.com, sj@kernel.org, weixugc@google.com, ying.huang@linux.alibaba.com, ziy@nvidia.com, dave@stgolabs.net, nifan.cxl@gmail.com, xuezhengchu@huawei.com, yiannis@zptcorp.com, akpm@linux-foundation.org, david@redhat.com, byungchul@sk.com, kinseyho@google.com, joshua.hahnjy@gmail.com, yuanchu@google.com, balbirs@nvidia.com, alok.rathore@samsung.com Subject: Re: [RFC PATCH v2 0/8] mm: Hot page tracking and promotion infrastructure Message-ID: References: <20250910144653.212066-1-bharata@amd.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20250910144653.212066-1-bharata@amd.com> X-Stat-Signature: aeokcxsa3fdr68a1ekfkhosjd34hz6cd X-Rspam-User: X-Rspamd-Queue-Id: B6614180006 X-Rspamd-Server: rspam04 X-HE-Tag: 1757518765-994996 X-HE-Meta: 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 dwvuNUYb mB5wAhUoHbwkzSCDuTJXmG64X4xcnF8BvzxMcXjYiMM0myJCQ31lCUggp0SjLvkYasRSEJ6dxr7HNZZE5L9FG+CUG1iLmgHEtNNv+jmgvoQHtFHBAuLYVTm3cvbsCu+EtlueS8G4RSqbJ/mHe3h95V8EFL6g8io5sZP0zZkg19aSvsfZpREF7MxTfflXiNTpa1Xp8qHwr1kHpSXiM2Goa6+YsHbX2uDR3bEbC+2Ww0oYdGsmQlY9yMzOZZYCiGowK4ESwj4iFQZv69BZ00de8AZfBPg== 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: On Wed, Sep 10, 2025 at 08:16:45PM +0530, Bharata B Rao wrote: > This patchset introduces a new subsystem for hot page tracking > and promotion (pghot) that consolidates memory access information > from various sources and enables centralized promotion of hot > pages across memory tiers. Just to be clear, I continue to believe this is a terrible idea and we should not do this. If systems will be built with CXL (and given the horrendous performance, I cannot see why they would be), the kernel should not be migrating memory around like this.