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[173.79.60.52]) by smtp.gmail.com with ESMTPSA id af79cd13be357-932de6724a4sm904385185a.43.2026.07.28.11.57.15 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Tue, 28 Jul 2026 11:57:16 -0700 (PDT) Date: Tue, 28 Jul 2026 14:57:10 -0400 From: Gregory Price To: Matthew Wilcox Cc: Andrew Morton , Bharata B Rao , linux-kernel@vger.kernel.org, linux-mm@kvack.org, Jonathan.Cameron@huawei.com, dave.hansen@intel.com, 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, david@kernel.org, byungchul@sk.com, kinseyho@google.com, joshua.hahnjy@gmail.com, yuanchu@google.com, balbirs@nvidia.com, alok.rathore@samsung.com, shivankg@amd.com, donettom@linux.ibm.com Subject: Re: [PATCH v8 0/8] mm: Hot page tracking and promotion infrastructure Message-ID: References: <20260728054356.291998-1-bharata@amd.com> <20260728111401.b6d674baf8e56a27c55e0c52@linux-foundation.org> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: X-Rspamd-Queue-Id: DEEDB12000E X-Stat-Signature: 6sj9ir4bsdpfyr9xd78sd77ux918yoxa X-Rspam-User: X-Rspamd-Server: rspam02 X-HE-Tag: 1785265037-568268 X-HE-Meta: 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 sPcP76fY 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 Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: List-Subscribe: List-Unsubscribe: On Tue, Jul 28, 2026 at 07:24:46PM +0100, Matthew Wilcox wrote: > On Tue, Jul 28, 2026 at 11:14:01AM -0700, Andrew Morton wrote: > > On Tue, 28 Jul 2026 11:13:48 +0530 Bharata B Rao wrote: > > > > > This patchset introduces pghot, a subsystem for hot page tracking and > > > promotion. > > > > Can DAMON be used to do this sort of thing adequately? > > > > Thanks, I'll await review input on this. > > I don't think we should do this. I don't think it's a use-case that > customers actually want; I think it's something CPU vendors think their > customers want. I've said this repeatedly over the months this patchset > has been in development. I say no. > I've been consistent about saying we (Meta) have been actively interested in this work and helping to drive the design of it. So it's not simply something born out of a CPU vendor think tank, we're actively working on solving real problems with it. I don't have data I can share now, but I think it's fair to wait for that data before faith-merging this on the hopes it's impactful. It does make it more difficult for us to do fleet-scale testing without it being upstream, but we'll get something. Tiered memory is being deployed aggressively [0] for considerable value, and is here to stay - like it or not. ~Gregory [0] https://jovans2.github.io/files/vistara_camera_ready.pdf