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[173.79.60.52]) by smtp.gmail.com with ESMTPSA id af79cd13be357-933d325ade8sm489716185a.12.2026.07.30.13.49.26 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Thu, 30 Jul 2026 13:49:26 -0700 (PDT) Date: Thu, 30 Jul 2026 16:49:24 -0400 From: Gregory Price To: Johannes Weiner Cc: Frank van der Linden , Yiannis Nikolakopoulos , Thomas Gleixner , Ingo Molnar , Borislav Petkov , Dave Hansen , x86@kernel.org, "H. Peter Anvin" , Andrew Morton , David Hildenbrand , Lorenzo Stoakes , "Liam R. Howlett" , Vlastimil Babka , Mike Rapoport , Suren Baghdasaryan , Michal Hocko , Trond Myklebust , Anna Schumaker , Zi Yan , Matthew Brost , Joshua Hahn , Rakie Kim , Byungchul Park , Ying Huang , Alistair Popple , Steven Rostedt , Masami Hiramatsu , Mathieu Desnoyers , Brendan Jackman , David Rientjes , Davidlohr Bueso , Fan Ni , Jonathan Cameron , Raghavendra K T , "Rao, Bharata Bhasker" , SeongJae Park , Wei Xu , Xuezheng Chu , Yiannis Nikolakopoulos , dimitrios@palyvos.net, Ryan Roberts , Huan Nguyen , linux-kernel@vger.kernel.org, linux-mm@kvack.org, linux-nfs@vger.kernel.org, linux-trace-kernel@vger.kernel.org, Alirad Malek Subject: Re: [PATCH RFC v2 0/3] Demote to lower tier using non-temporal stores Message-ID: References: <20260730-rfc-nt-demote-v2-0-452dbe3b5073@zptcorp.com> MIME-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Disposition: inline Content-Transfer-Encoding: 8bit In-Reply-To: X-Stat-Signature: mito1s8dis8kuenkdf4my9zcxucnwwpx X-Rspam-User: X-Rspamd-Server: rspam11 X-Rspamd-Queue-Id: 5A3D3120004 X-HE-Tag: 1785444568-756466 X-HE-Meta: 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 zhfxB4al YmE72dCGdoCUA3J2MTW7jc5zaCkdIKI3YrcfgwpbY7jP4aMAvVcffRfvtgtfM/Er9froaI3v9HaOSeb5Ir55MuB4gIGHPJKpEQCvWXAXD0m3v65DQW6nVgGa9IvF7YVt/9dPv/E3TCpSSEnHUpW/e5GIDOSEBCVyzSZaeFI98bHKkDKHp9PB+lJkSEvpA9dY/wvdDGS3XkSmv+khci+1ha+qVtZwgJTgTeAtHXAHd/ukWR2XVcgeaVGZRm8cNiaWtbz1GSZpeH98Y4vzo7NwsIF/0kpQzsQeEqIpg1MAOxcuDojGbnRlZg4HKuqF/p7eO6a28dC6ztxLnGlXfzEtt0tDgTSuD8mUdx6fIkNIpGjHmvuaukF+Ez9s83NlMhFRTVFFun+HPzxiDa64vtT5usaJoLklSWFGXkzJFcmjvIUOjNr0vyrONac8MslCCF9LVLILpzz8sWFIyaKAWThnvN3xqeCZTtlG0IxlySR3I498EB4Q= Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: List-Subscribe: List-Unsubscribe: On Thu, Jul 30, 2026 at 02:08:56PM -0400, Johannes Weiner wrote: > On Thu, Jul 30, 2026 at 10:40:32AM -0700, Frank van der Linden wrote: > > On Thu, Jul 30, 2026 at 10:30 AM Gregory Price wrote: > > > arm64 already seems to use stores with NT hints by default. > > > > In general, though, I agree that for ASYNC requests, just always using > > NT seems fine. > > > > Maybe the mode and reason should be folded in to one variable, so > > that, further down the stack, a decision can be made as to what type > > of copy to use? E.g. if the mode is !MIGRATE_ASYNC and the reason is > > MR_DEMOTION, then non-temporal is still a good choice. If the mode is > > MIGRATE_ASYNC, NT is still a good idea. If you wanted to get fancy, > > any mode with folio_test_waiters(folio) == true should not use NT, > > since a task is waiting to use the data, so caching it is better. > > Maybe that's overthinking it. > > Agree. `reason' seems like a much stronger signal. I think this ends up cleaner as well, it would be a nice improvement. ~Gregory