From mboxrd@z Thu Jan 1 00:00:00 1970 Authentication-Results: smtp.subspace.kernel.org; arc=pass header.oldest-pass=0 smtp.remote-ip=209.85.160.169 ARC-Seal: i=2; d=subspace.kernel.org; s=arc20261015; a=rsa-sha256; cv=pass; t=1794524823; b=CZB9w4/7iaM3FskeJMPl827vhrbJmUtGlv+655caXq9hpNBVre1Lrdmxcfo0YsEUYNCA L+JZc+o/zhaHNMzonArAawrEVm5K/RYFRf9m+My8KG/izHHRcZoGeIvyGdrVxfctDDZDQ B9RTz3oMvgYyn+gFqznRsECGknZ2W+GYw1eT0HFQj0t4LythI6vWJv988d5x7bAdixJN+ sZbx95koDdCjPfIDWbKpJfLS9bAwGyEOrrUyXjAeXEUIMNCAvng0evxymgHhepfPNsOPk hzD9UCPF7m+bAeAloccsJrsqIHAUVfuDGwbvQWqTb538hDXxPH569K9PdedKqR2qNXw== ARC-Message-Signature: i=2; d=subspace.kernel.org; s=arc20261015; a=rsa-sha256; c=relaxed/relaxed; t=1794524823; h=DMARC-Filter:Received:DKIM-Signature:X-Google-DKIM-Signature: X-Forwarded-Encrypted:X-Gm-Message-State:X-Gm-Gg:X-Received: MIME-Version:References:In-Reply-To:From:Date:X-Gm-Features: Message-ID:Subject:To:Cc:Content-Type:Content-Transfer-Encoding; bh=iq7zuX4mescGycMYtdVsnHt3n8ea5BUsLeUaRpIODWM=; b=iP+p10nUyz7UyLLG5hx7+0EIxCJTgIV4HtHEdtfXuxaHbpRJ3ux9VhMOFPQ2wWNodZe/ y7pZ2MrwP/Pv7Pb7/pSPHpTkFKItY/I/rUnmdhHh3WNUJUSjl8Gw+7A9jBoucviMfY2zU PB29oZGWzEJtc0f0tbhBjIcqKhOt7hMfz+hbcvxNDasuKaz7PeMU+hlfnIDvtTqTAisnt UY1FatYhz2isBbKe2/EF35CL5rJ+7Tst77TgB9SB1mVplKqnpO8ux+4ua+ZCF9an6MILH E7bEat0d3wJJenQAy5K+bZlXrQ6TzPtMPtfVlPHvKgD1WRhQz8Db59Bg33aXG9s4IKA== ARC-Authentication-Results: i=2; smtp.subspace.kernel.org; dmarc=pass header.from=google.com; spf=pass smtp.mailfrom=google.com; dkim=pass header.d=google.com header.i=@google.com header.a=rsa-sha256 header.s=20260707 header.b=irICtOrg; arc=pass header.oldest-pass=0 smtp.remote-ip=209.85.160.169 Received: from mail-qt1-f169.google.com (mail-qt1-f169.google.com [209.85.160.169]) (using TLSv1.3 with cipher TLS_AES_128_GCM_SHA256 (128/128 bits) key-exchange X25519 server-signature ECDSA (prime256v1) server-digest SHA256) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id F27A9606A321 for ; Thu, 12 Nov 2026 23:07:02 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.4.2 smtp.subspace.kernel.org F27A9606A321 Authentication-Results: smtp.subspace.kernel.org; dmarc=pass (p=reject dis=none) header.from=google.com Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=google.com Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=google.com header.i=@google.com header.a=rsa-sha256 header.s=20260707 header.b=irICtOrg Received: by mail-qt1-f169.google.com with SMTP id d75a77b69052e-54492d8a988so18311cf.0 for ; Thu, 12 Nov 2026 15:07:02 -0800 (PST) ARC-Seal: i=1; a=rsa-sha256; t=1794524822; cv=none; d=google.com; s=arc-20260327; b=HwxlSgMHhZKPLKqcXdei6w9xF8vT5xI7Zm6xHUU0qHfJEU/HWprU0nc4I4bYU+9oEG U2CMp2352VJT3sxIvvkdRiN8lDBFhQcuSH07UWVdhiY61ZqeusnpA9uryFrBozOP86pI 3eGJL6xjOZRwsCJoLkk4fxYZhG5lzOM6YoW+F654maBlXzT23syYcX2JDnUyKOHxQGXB 2tEidQAgeaP8XyG0HBKW7Hum363j453kqZUqRZwk9GickwSHtsDPrvxae9iYOOeVXzBK TjqxtDpdw815/LPI6TG3KxMUs6DPb0wEtRCdKJbTLWkA+uts1zLUpHwPl7/YeigbszQo BvLg== ARC-Message-Signature: i=1; a=rsa-sha256; c=relaxed/relaxed; d=google.com; s=arc-20260327; h=content-transfer-encoding:cc:to:subject:message-id:date:from :in-reply-to:references:mime-version:dkim-signature; bh=iq7zuX4mescGycMYtdVsnHt3n8ea5BUsLeUaRpIODWM=; fh=i+Nh5WFQTlyYCY5y5kvCtADmqySeogVqFXv1YzU8POY=; b=AMI5PVScU2PRlvOHHQo0/M5oG193H7mp44nY+EQuLHLTWsY6T7V0Mz0Hvnn36NTHst 3wfhheAU+QRGaDloKFF4VQ+8b00LrizvPvhLru/nISdsMdAQ4AAv49xJgicc0CQHl0xl zXEXGiiarGeYgvduytRH/o7ZATsjqPW8Lh4OLnztIxeyPW0ry1uh8cv/ncnO4rDx4rFI mvFlU67KLW7D0wP+PD36+p6bYPbdKtCJttJCwlO+Jy+tD3f3IxVguOvRyl7NVRULcpGF z8ssgzLF/I4+hVfswdAQ4qxZJNfh5LnVYtcxqpz3zDsBmTbH9ZyE/26+nJpDTfQpD3Bt wShg==; darn=vger.kernel.org ARC-Authentication-Results: i=1; mx.google.com; arc=none DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=google.com; s=20260707; t=1794524822; x=1795129622; darn=vger.kernel.org; h=content-transfer-encoding:content-type:cc:to:subject:message-id :date:from:in-reply-to:references:mime-version:from:to:cc:subject :date:message-id:reply-to:content-type; bh=iq7zuX4mescGycMYtdVsnHt3n8ea5BUsLeUaRpIODWM=; b=irICtOrgRGFSY53WuIyzu8TvH4VAFbp2Bm9vZ4Z1Z94hZozwaMXLPxyJx/tlti2mVi ctcdxtiTUfyI8LFpkjubrWADm37oXauz/yIIo60ytVeIRG1VBoLNFIiuy0k+6Ju3jFQd 7REtp4u2l3gQJoyCxJncqUbeCGAoNHXHbZ6REFJqvzb2PcXCrmukCEXpQXNOYn1sLXrs ICu8svIF5y41B/8N5MbGb9qnQrAt5rMNJoRqqozkRerVUe62lhc7jCnCfoDqB6sF60RT LV5VmLgNaudkTgH3dH1fHWPWHdcavn/h+HTTkV/FsVRJr8IIipcHA5Up6ArQIs0x8H9P b6ow== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20260707; t=1794524822; x=1795129622; h=content-transfer-encoding:content-type:cc:to:subject:message-id :date:from:in-reply-to:references:mime-version:x-gm-gg :x-gm-message-state:from:to:cc:subject:date:message-id:reply-to :content-type; bh=iq7zuX4mescGycMYtdVsnHt3n8ea5BUsLeUaRpIODWM=; b=cbfi+SR0HJA0ychGPUMQLIJdtGLv3PdtkZmL8W3aR7VsvsV5CAwZEps2rD7TUoIskc 54a0RRq+BWQXhxsr/sVYbDrCtm5+yHCV5qMMAEdAqma1HHwzIKJRD7qk+OCWdHoGeH+5 mcYwdqVjiv1jE96nhqnNHcCr1W6hIaJjrZV/U8Tl0Gk47ae08b2WwmLkGQ7euqxG7eee 9ICm09+B5TxPOi4357e+B3KICB3LJ1Jt0y1shJtAZXbVaRcGYUVgGcfjGJWVO57qdg0c jT6xrYH66WhtqRapfJXtGOloj8HqhmdxV01PsgrL2fJvBwi9Gr5UKtiUm8bSw+7IK3kd zNnA== X-Forwarded-Encrypted: i=1; AL+hErErwztvItZrkwzl2/PZfKB9/WHUM/B+tVwvUHnrMNJY7x4Ag5MTudFnkDwCSmJnkYmMMuOYbMft28FnNYk=@vger.kernel.org X-Gm-Message-State: APuU4Z/oGDcgR5wJKe+qyeNu0We4hx/0DiDPCipa/sXof5Mp8oIcj7iH EEU6HMdR5QtF/msyqyeCMclAsRnazcLJ8i/EXCoeokAEcfpjRsuPIYZIUxF5uOmySWSfLctukm2 Nu3k+7gjB6atcOTtUFDAUaW6+soXPUcfsquQLTiPR X-Gm-Gg: AYBFou39MrphE6U2zpmpC1kMMtexo5Sh2hyr8cxLQgZu/1rdUNuerBrpyrAiGr6sNjv rEphYREvCV8W/9QF8ggzX3acu1MSyYclPA6U3svDR1yTalg3rNr9Y/U0aRZxLEAVN4+fohA9yz6 1UCCIdcNEokxF+tLReHqOA/qF9yAgwHRHxjlsqqUY+rThMUT/UHj6ravWdXkMoqTHo8Z+JPhlyL gOgtJ73BRuZeST+o56ApOH6SaWXyytI0woFfl/aLdV2VjM/mMQPrEiZjP7fITsHlMA1DbVm25p7 12eMdIOXVQ137em2jQEr50tOaexGsbcqdv2avLsUT8xIJYyLEBu08Q2Tx22y0Ksdu6ZA7EymzRb kXFKQIGchS5nrnwMINRo9Odg+PYZvr1NbbK1npOhTwieFXSyh2uTMvAymUI7z4c7lmc3BsyQh41 1ThTk1bVYXC/v8 X-Received: by 2002:a05:622a:4885:b0:536:3ee4:81cd with SMTP id d75a77b69052e-55adb2a6457mr5607171cf.4.1794524821197; Thu, 12 Nov 2026 15:07:01 -0800 (PST) X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Post: List-Help: List-Subscribe: List-Unsubscribe: List-Owner: Precedence: list MIME-Version: 1.0 References: <20260730-rfc-nt-demote-v2-0-452dbe3b5073@zptcorp.com> <20261103223025.2482227-1-nhuhuan@google.com> <7CF5AD15-B833-44E1-A9FE-C8E12F8C9E82@nvidia.com> In-Reply-To: <7CF5AD15-B833-44E1-A9FE-C8E12F8C9E82@nvidia.com> From: Huan Nguyen Date: Thu, 12 Nov 2026 15:06:23 -0800 X-Gm-Features: AclHuK8R0WzJXR4yHYxHSMICSWxLr-x7bnN-BX27nSJiTtbJXgPCv-FYzS8TYcg Message-ID: Subject: Re: [RFC PATCH v3 0/3] mm: use non-temporal stores for demotion To: Zi Yan Cc: tglx@kernel.org, mingo@redhat.com, bp@alien8.de, dave.hansen@linux.intel.com, x86@kernel.org, hpa@zytor.com, akpm@linux-foundation.org, david@kernel.org, ljs@kernel.org, Liam.Howlett@oracle.com, vbabka@kernel.org, rppt@kernel.org, surenb@google.com, mhocko@suse.com, trondmy@kernel.org, anna@kernel.org, matthew.brost@intel.com, joshua.hahnjy@gmail.com, rakie.kim@sk.com, byungchul@sk.com, gourry@gourry.net, ying.huang@linux.alibaba.com, apopple@nvidia.com, rostedt@goodmis.org, mhiramat@kernel.org, mathieu.desnoyers@efficios.com, jackmanb@google.com, hannes@cmpxchg.org, shivankg@amd.com, rientjes@google.com, dave@stgolabs.net, nifan.cxl@gmail.com, fvdl@google.com, jic23@kernel.org, rkodsara@amd.com, bharata@amd.com, sj@kernel.org, weixugc@google.com, xuezhengchu@huawei.com, yiannis@zptcorp.com, yiannis.nikolakop@gmail.com, dimitrios.palyvos@zptcorp.com, alirad.malek@zptcorp.com, ryan.roberts@arm.com, linux-kernel@vger.kernel.org, linux-mm@kvack.org, linux-nfs@vger.kernel.org, linux-trace-kernel@vger.kernel.org Content-Type: text/plain; charset="UTF-8" Content-Transfer-Encoding: quoted-printable On Tue, Nov 3, 2026 at 4:09=E2=80=AFPM Zi Yan wrote: > > On 3 Nov 2026, at 17:30, Huan Nguyen wrote: > > > This series continues the non-temporal demotion work originally posted > > by Yiannis Nikolakopoulos [1]. > > > > Motivation > > =3D=3D=3D=3D=3D=3D=3D=3D=3D=3D > > Memory tier demotion moves cold folios from local DRAM to slower memory > > tiers, such as CXL or remote NUMA nodes. Standard store instructions > > force the CPU to allocate cache lines for cold data that is unlikely to > > be referenced in the near term. > > > > Using non-temporal stores and prefetching on x86 bypasses CPU cache > > allocation, protecting active workload working sets and improving > > demotion throughput. > > > > Changes in v3 > > =3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D > > - Unified MCE-safe NT copy (addressing v2 Open #1): > > Implement copy_mc_page_nt() in x86 assembly to provide machine-check > > safe copying using non-temporal stores (movnti) and prefetchnta. > > > > - Architecture abstraction (addressing v2 Open #2): > > v2 relied on memcpy_flushcache(), which lacks non-temporal stores on > > architectures like arm64. RFC v3 replaces this with a dedicated > > __HAVE_ARCH_COPY_PAGE_NT interface and generic fallback, enabling > > architectures to plug in native non-temporal routines independently. > > > > - Memory ordering: > > Add a wmb() barrier at the end of folio_mc_copy_nt() to ensure weakly > > ordered non-temporal stores are drained before page tables are update= d. > > > > Discussions > > =3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D > > 1. Migration mode vs. migration control refactoring: > > Currently, this series introduces MIGRATE_ASYNC_NONTEMPORAL into > > enum migrate_mode. In parallel, Shivank Garg's migration refactoring > > series [2] consolidates migration arguments into migrate_control. > > Once that lands, demotion can simply rely on the migration reason > > instead of adding a dedicated migration mode and helper. > > If that is the ultimate goal, why not do it in this series to avoid > code churn? You probably can coordinate with Shivank on how to move > the migration control refactoring code to this series. Thanks for the suggestion. I reached out to Shivank and we are coordinating on this. Best, Huan