From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from smtp.kernel.org (aws-us-west-2-korg-mail-alma10-1.taild15c8.ts.net [100.103.45.18]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id E95E23B961B for ; Tue, 28 Jul 2026 19:20:44 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=100.103.45.18 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1785266446; cv=none; b=S+upJvNu/VdcLBMuY6ppdGPr32kpksADxDQiFyDem7cbyQG3A2NqZksXxQA/bRnXe8Vn66Px7tYjNPHhjdszUKRUcm/CM9KX0DdwqCKEKzMxwKT0xtAbZu6nCzazFCem0grzQzvQyao6S636m5Dlk9jDqNwEjtFrVlooPrPgqsg= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1785266446; c=relaxed/simple; bh=F4GaWBQXxRqPU2MEs9OWZ4YCcMx0Pms1hzD4wz0jVzY=; h=Message-ID:Date:MIME-Version:Subject:To:Cc:References:From: In-Reply-To:Content-Type; b=LyJ7GrBBjtgAb1C+MNWR+HUXIIwEq4g14To+kNVNrExD0p7cVMLn2OTyribOqLUkD2eHAlj/u7k6NLfxLi9yRQwTo/UwomechB1WOUE3eNMoYUnXiVh1u6FWWoPGQ4oMJHx+Mo2Q4UNMAtk3Z8nsIIRJvvNnhfbYAWUZQFlrZ4M= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b=UoSsGgyp; arc=none smtp.client-ip=100.103.45.18 Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b="UoSsGgyp" Received: by smtp.kernel.org (Postfix) with ESMTPSA id 084891F000E9; Tue, 28 Jul 2026 19:20:34 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=kernel.org; s=k20260515; t=1785266443; bh=MF5VoMwEnUVISBu/dFwWaOtJBONrOWPjC0YQh5tRsCA=; h=Date:Subject:To:Cc:References:From:In-Reply-To; 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 Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: 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 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