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Shutemov" , Dave Hansen , Andy Lutomirski , x86@kernel.org, Kostya Serebryany , Andrey Ryabinin , Andrey Konovalov , Alexander Potapenko , Taras Madan , Dmitry Vyukov , "H . J . Lu" , Andi Kleen , Rick Edgecombe , Bharata B Rao , Jacob Pan , Ashok Raj , linux-mm@kvack.org, linux-kernel@vger.kernel.org, Sami Tolvanen , ndesaulniers@google.com, joao@overdrivepizza.com Subject: Re: [PATCHv14 08/17] x86/mm: Reduce untagged_addr() overhead until the first LAM user Message-ID: References: <20230111123736.20025-1-kirill.shutemov@linux.intel.com> <20230111123736.20025-9-kirill.shutemov@linux.intel.com> <20230117135703.voaumisreld7crfb@box> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: X-Rspamd-Queue-Id: 3FA6F40014 X-Stat-Signature: bnmrhuczc9nxy18c64xo3rpxgink899j X-Rspam-User: X-Rspamd-Server: rspam08 X-HE-Tag: 1673979693-20802 X-HE-Meta: U2FsdGVkX1/bsAwHPoKM+ezDG/V5TnZ2spZFMz3zbAVv7gyxy+18BX9kJwR2fIZ+Fn4m1iOPsSo9uaBXlHsTj6x2BvIaEVXwSrL0AMzy4M+QHtX0luC0nYFtbmSHTAcpQ8e2Muexn7c+cjChDfn9WTMUQF8uAAbyPfHuKQdU6V8Pwjh9YJXFYmkqV6wUdgLdcqUwSzfh4QwoeLUtdbMxjmNvGZF7BiPi/Ew2tOPelfsRhe9E3Sq2ST5jIk0DWQba5DO18Jx62jepsuZjV/5R7e3LUDxOHqufknpwGiJ0qNMOzCr2Wup3mMXLV8y15J3dgJJvhvgN/YlSuySEJWDZRXJWjHNwzYOTcuwXLQ6QwWOBWzU6ZNdxYgADd3JWZH1hvA7Oe8PoMoG7MpVJ7dRg/XDo7E7kPkpgDsy8SCiP9ZG7epxP19ZIuM7IfGjLkRuvVur//4KGUiJ/zYApYIUMX9Pi5+3jGTXeU2uqzMOSHqzr21dLx+MSCOpKVpwdOsCivwKj7aDwvmILmzmmmFOMROW2yx4LgrgpbtHa5TNnPtg8P3qD4QszmqJUVqbkrz9uNNmnxcF4T//gNmTCEdReW0NjZTDV0BSLH4sZmvO0oW5mclbTWatCkaU0HXUKv/iR3tLwN+fw45qA/NcTddQyuxO+ZQdArTGxR4HzhorRjOo0HRe0D0gb6Kxk0zayaNpvLTqgf9A9npYWc0QMF4Tbt3NX6CJg/LkV6y8qsA3Wn/4TrekxojgnJLsxqvv8ZLP7ds9OKu8xPiItMQQeNqM0yRWASnFTHfbBcsQjH7O6V67bO0TgXnxA8ignAR6Nv2HSdnqpHv91BEdGP+K2kDx+25RD6a056Pe9lRSNPn+1pTdqqbLC6uq/6iJqZ42SieppwyFFVRfuSpnfAQcu64o6ov/N4wmRGTQ+qeqjsPeatJB9j6a5oBM0vBtVZ3wD1i5juEEhvzzOFYsnyQZrTCq bwbLok7G /dPxO X-Bogosity: Ham, tests=bogofilter, spamicity=0.000000, version=1.2.4 Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: On Tue, Jan 17, 2023 at 09:18:01AM -0800, Linus Torvalds wrote: > But maybe even those aren't worth worrying about. At least they do the > unmasking outside the loop - although then in the case of execve(), > the string copies themselves are obviously done in a loop anyway. > > Kirill, do you have clear numbers for that static key being a noticeable win? Numbers would be good; I think this all started as a precaution, but clearly that's not really working out so well :/