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Tue, 04 Aug 2026 15:01:21 -0700 (PDT) Date: Tue, 4 Aug 2026 15:01:21 -0700 (PDT) From: "Christoph Lameter (Ampere)" To: "David Hildenbrand (Arm)" cc: "Lorenzo Stoakes (ARM)" , Mark Rutland , Yang Shi , Ryan Roberts , dennis@kernel.org, tj@kernel.org, urezki@gmail.com, catalin.marinas@arm.com, will@kernel.org, akpm@linux-foundation.org, hca@linux.ibm.com, gor@linux.ibm.com, agordeev@linux.ibm.com, linux-mm@kvack.org, linux-arm-kernel@lists.infradead.org, linux-kernel@vger.kernel.org, Linus Torvalds , Jason Gunthorpe Subject: Re: [RFC v2 PATCH 0/16] Optimize this_cpu_*() ops for non-x86 (ARM64 for this series) In-Reply-To: Message-ID: References: <20260715180455.515692-1-yang@os.amperecomputing.com> <0344c559-1959-4531-9265-d5a5180eb7cd@arm.com> <25d1e09b-53e4-7cd5-87db-b58437e4e690@gentwo.org> <4887267b-dc26-4c33-96ca-8dff054a0d1f@kernel.org> <63ea8156-a109-b2a2-6d35-1c17ad7f1a9d@gentwo.org> <84b31836-1d10-4bec-a469-468b91fd4645@kernel.org> <9f146ce0-4adc-0c00-a2d8-c01b47edc9d1@gentwo.org> MIME-Version: 1.0 Content-Type: text/plain; charset=US-ASCII X-Rspamd-Server: rspam09 X-Rspamd-Queue-Id: 3EEC41C0008 X-Stat-Signature: jhztdzdkuf79j4pzqiykbuz8mhhdguqo X-Rspam-User: X-HE-Tag: 1785882755-439456 X-HE-Meta: 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 v8paXtBE QzE6YRuIfMYdKjKbDzDIM17JRDDwRt4J0GZvEdYu2yGAK0vX5bbbIKJnHt+4ez/VyT0xLGDG4XXvkJ0fVFdDl3Lu6uLkYaabOxT4jMubRl1gY4n5a2355bAWtFELbXj/tiK7sfLLfph2a2KBugz5p5gqzWaP5T20wP5CiYSwKDwO45iQbEQjmlNy9ikl04wzOdLm7DxOhIP4aYt0CP6tGcmBb2tyaW0RnDHznbV71WR5hlNeqrPNYPwUBQpXT9LSr5CcLhC60UgQxNUjWlBfHlJ+F1iAEuS6UWBPGIH7Z9wuacsM= Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: List-Subscribe: List-Unsubscribe: On Tue, 4 Aug 2026, David Hildenbrand (Arm) wrote: > >> If the proposed solution has a significant benefit over Mark's solution it could > >> be discussed as a next step; and it must be backed with sufficient data to > >> warrant all this complexity here. > > > > You cannot accept that one instruction is faster than the same > > instruction prefixed with another and something else at its tail? > > I am pretty sure that you got exactly what I meant, you likely just don't have > the data to back it up. > > Proof me wrong! Well you seem to have alrady seen the benchmarks that we ran and are running. So I had doubts on your sincerety with this comment. Seemes to be be just there for effect.