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b=sv7n1QElgb76rqGToIAUTZedLTS/X9qMA6j8l+9hRUdBY0E+pxb/5+Ltz7rkDnIgm zaONW59Qxi1ad6w0pkPNwKCkuqvuyEZ6MszSUEsBKesg37khLpOcLkGa8y4OBwsM1Y ERXZeEI2P2t2rBRKrjKPjthF4uRmzOYTheF+HgBg= Date: Wed, 15 Nov 2023 13:37:43 -0800 From: Andrew Morton To: Ryan Roberts Cc: Catalin Marinas , Will Deacon , Ard Biesheuvel , Marc Zyngier , Oliver Upton , James Morse , Suzuki K Poulose , Zenghui Yu , Andrey Ryabinin , Alexander Potapenko , Andrey Konovalov , Dmitry Vyukov , Vincenzo Frascino , Anshuman Khandual , Matthew Wilcox , Yu Zhao , Mark Rutland , David Hildenbrand , Kefeng Wang , John Hubbard , Zi Yan , linux-arm-kernel@lists.infradead.org, linux-mm@kvack.org, linux-kernel@vger.kernel.org Subject: Re: [PATCH v2 01/14] mm: Batch-copy PTE ranges during fork() Message-Id: <20231115133743.674690dc78041768b79fadd9@linux-foundation.org> In-Reply-To: <20231115163018.1303287-2-ryan.roberts@arm.com> References: <20231115163018.1303287-1-ryan.roberts@arm.com> <20231115163018.1303287-2-ryan.roberts@arm.com> X-Mailer: Sylpheed 3.8.0beta1 (GTK+ 2.24.33; x86_64-pc-linux-gnu) Mime-Version: 1.0 Content-Type: text/plain; charset=US-ASCII Content-Transfer-Encoding: 7bit X-Rspamd-Queue-Id: C938FA000F X-Rspam-User: X-Rspamd-Server: rspam05 X-Stat-Signature: 4awoghqa4act5ga7kqy56bgz7dopmzwd X-HE-Tag: 1700084266-136336 X-HE-Meta: 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 dAQ2nVcK 2Nd2h4qK9ZXwweX1m2MTDb29Yz52ekam7Wl0kicwSbRpOxagETzLrwgG6n84KD5KRDNa8E6g00ohxF9rqa7U5Uw/cD7CSzz/HJGkYhvogl6w6DD8lbZohZntbw5gdEyDWl/MwnTVII/wtb+ZuShLrpNvnSEOR1jTrY2feoYlMvH/uvXxxyLjPf+xx1j2l3l/04dD/6bcgZdilbsi+/kldPn8pGuehDCUKOUBxGGPp2cjLO1PKUrrYL8fgiLAmMkb4QutimtR8GWD7BuHlvPOfgSdgrztEjDVeawnAe3pcmsGlsdXeAAlIASkoCLxsowGjLEX+flxnt9KVt9RI5kksA+A780Z5kPYdOCtWE2FkuSIXJik= 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: List-Subscribe: List-Unsubscribe: On Wed, 15 Nov 2023 16:30:05 +0000 Ryan Roberts wrote: > However, the primary motivation for this change is to reduce the number > of tlb maintenance operations that the arm64 backend has to perform > during fork Do you have a feeling for how much performance improved due to this? Are there other architectures which might similarly benefit? By implementing ptep_set_wrprotects(), it appears. If so, what sort of gains might they see?