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b=UoSsGgyprqujUEoEwo3IWrczV2nXTypjWlduC39SIC5D1C4LMzurogequIdI+/YRP 2bfp3ATBpM+Z/wPJUH+gBg39Dp2Xrk0OQZv/uLQlIdtB/1O72zsLfVoa8Bot5loDNN 0ZBbu6ON8gtyKuSZnlk9GD83BNiMAyHsY/w6k2hoBiSxr4cfsNKuTxdtZzwRYztAuk CVpay9DMSJ72b61t8hkML59aGT4IWsU0Wd2QwiAigIy5Gnk72UgT1jKtdA85YL1oDn oi8HebVh2DBWxB3wYxi3lN+xG7sCQU3JMmQ4v433hGuBgKAwTERp8H+1YsFr4ssD9Z nbFNEtHyEDL2w== Message-ID: Date: Tue, 28 Jul 2026 21:20:32 +0200 MIME-Version: 1.0 User-Agent: Mozilla Thunderbird Subject: Re: [PATCH v8 0/8] mm: Hot page tracking and promotion infrastructure To: Gregory Price , 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, 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 References: <20260728054356.291998-1-bharata@amd.com> <20260728111401.b6d674baf8e56a27c55e0c52@linux-foundation.org> From: "David Hildenbrand (Arm)" Content-Language: en-US Autocrypt: addr=david@kernel.org; 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charset=UTF-8 Content-Transfer-Encoding: 7bit X-Rspamd-Server: rspam10 X-Rspamd-Queue-Id: 728FC1C000C X-Stat-Signature: 58r7j1ctmetn5tz8976641j8tbh7888q X-Rspam-User: X-HE-Tag: 1785266444-873330 X-HE-Meta: U2FsdGVkX1+4ck/f8dau8mwceVoyF5lBqAoFC+v0fd08JhFuH6qQYJ/UTd5Y1mefjPMubx3Vx/SEsxRcX619ngjAdcLOmm6h1OiHObpLDgwMtJSU6cuRenMWq8M52VadDBE8+OyiNwbpe7QDobzNdTm0Rd8DZo62S6T6nbgg5i4GEcXehCVr6h8FaiPfPxH60Mj7/uANVik4PTD5f9+XWvy03YrN6jCDNUz1H7vKrKoF32dotK3TUSsc0W7z0YW4KcHBszsIro7flFSDsjKPkc8MART2axwnlwlkI4OqTbBvuq82HNiamNTrf0rfW4UYgatTYN8W17DrTDwPMaZgHmjbR2yHiJbVFUCOciRWRLZiZTBEoTUC+MnqqxQShcd0qrEYCxNP80Jbtxr+RX4yA7OjrSoi1COECZNxqfMQDDvcRer54wCLev3E092PzaZbgqOOhUOcIodGpZZs0pQV64Hc4fyvzXVdDGo72mk4Jem5GavLVsBJAolFFAmdzYjCkWcOcNBi75V1jmIi4HXOkopQhrwt8DgcnY1uhl9mRCwKeqRQsl1RcRRsovJW2n4Qseu4TrXPQjLFa3tPc/NGAGb1C+se4Y+YEFLm6lmoOQp9979Drcrsx5/d2dDk3ocUWWyFdX0Ff5chMJOglPP9kdWUoN9/j0fjOHHwkE1+fr9ygchHbnA+zhJhyswtxuLkdjOphsk/X/2kZrz1YQHOkWu9JgSqrhVzPRaiOuyRWpD7AsYVEN/T1PFUINkELXmOldrRGmGw4goi7kVMkzjgCqh97Bw2nISnaXe4ipEhswJoCKTjMSUjk7T1FqwX6GriwadyL/K29Due0+a0Va7h2Yt0CUoM2Ti7PbguEv7GmHRMjTvvoLcuf5Hy6acWt/WUptDRV7xQQcUHkb+PFS/eeI5oOIWl4VvoC91RblVlNnOmC2uYm/nr4gDBLj2pOJbTNeHIkHRpvrVnArPWmla dK8NsnfS 7Xj5dRJUlTrv/7MOTQkfTPjF4gMUni16u+UQAgU6GZxSH10psQsQZKHcZdjjiTgtHHdinIt9hdfvSfUXzNFjG92+qOSWcHUKUsA2+VP8H7JqMpDHpyP6b+mtFLU0WZwGrOQIZs+odOj1TZ2WRFt8XOB7rqZDZz1FPW2oIinK+Wg1TmeumeYKKOwY6dTJGcOLdShEWIQpaXP6GfJoCnVCQqm03gbihbg/Ti+BMvU1ZDkvB67MMYPIq4vdxH5+5yqB3bp5MAaMc+blQQGQhlOiWOzj/QEdYS5Nrh4oe5bfvhXNJXut09g7vZGPiJxBeZsU+HqiE/JIOIBITqWs= Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: List-Subscribe: List-Unsubscribe: On 7/28/26 20:57, Gregory Price wrote: > 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: >>> >>> >>> 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. The diffstat is scary, to say the least. And the x86 stuff certainly needs x86 maintainer acks. So far there is no real review -- we're in v8 without a single tag. So this is far away from being mergeable. I'm afraid this will need a lot more discussions, and likely RFC would have been still appropriate at this point. It's a shame this work was going on for quite a while without feedback (blame me if you want :) but there are only so many hours in a day), but the main problem is that this work in particular was not perceived to be high or even medium priority so far. -- Cheers, David