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([2001:b07:6468:f312:9af8:e5f5:7516:fa89]) by smtp.googlemail.com with ESMTPSA id z8-20020a1709067e4800b00977ecf6942bsm1036209ejr.90.2023.06.09.02.07.58 (version=TLS1_3 cipher=TLS_AES_128_GCM_SHA256 bits=128/128); Fri, 09 Jun 2023 02:08:00 -0700 (PDT) Message-ID: <26cf0b0a-cda5-08a9-a669-6966f9e626b1@redhat.com> Date: Fri, 9 Jun 2023 11:07:55 +0200 MIME-Version: 1.0 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:102.0) Gecko/20100101 Thunderbird/102.10.0 To: Yu Zhao , Andrew Morton Cc: Alistair Popple , Anup Patel , Ben Gardon , Borislav Petkov , Catalin Marinas , Chao Peng , Christophe Leroy , Dave Hansen , Fabiano Rosas , Gaosheng Cui , Gavin Shan , "H. Peter Anvin" , Ingo Molnar , James Morse , "Jason A. Donenfeld" , Jason Gunthorpe , Jonathan Corbet , Marc Zyngier , Masami Hiramatsu , Michael Ellerman , Michael Larabel , Mike Rapoport , Nicholas Piggin , Oliver Upton , Paul Mackerras , Peter Xu , Sean Christopherson , Steven Rostedt , Suzuki K Poulose , Thomas Gleixner , Thomas Huth , Will Deacon , Zenghui Yu , kvmarm@lists.linux.dev, kvm@vger.kernel.org, linux-arm-kernel@lists.infradead.org, linux-doc@vger.kernel.org, linux-kernel@vger.kernel.org, linux-mm@kvack.org, linuxppc-dev@lists.ozlabs.org, linux-trace-kernel@vger.kernel.org, x86@kernel.org, linux-mm@google.com References: <20230526234435.662652-1-yuzhao@google.com> From: Paolo Bonzini Subject: Re: [PATCH mm-unstable v2 00/10] mm/kvm: locklessly clear the accessed bit In-Reply-To: <20230526234435.662652-1-yuzhao@google.com> X-Mimecast-Spam-Score: 0 X-Mimecast-Originator: redhat.com Content-Language: en-US Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: 7bit X-Rspamd-Server: rspam08 X-Rspamd-Queue-Id: AABA414001F X-Stat-Signature: zzpkwc44pixgi6rjx8wpzk6su5b4jukp X-Rspam-User: X-HE-Tag: 1686301684-166988 X-HE-Meta: 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 xD7EDtIN 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 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 5/27/23 01:44, Yu Zhao wrote: > TLDR > ==== > This patchset adds a fast path to clear the accessed bit without > taking kvm->mmu_lock. It can significantly improve the performance of > guests when the host is under heavy memory pressure. > > ChromeOS has been using a similar approach [1] since mid 2021 and it > was proven successful on tens of millions devices. > > This v2 addressed previous requests [2] on refactoring code, removing > inaccurate/redundant texts, etc. > > [1]https://crrev.com/c/2987928 > [2]https://lore.kernel.org/r/20230217041230.2417228-1-yuzhao@google.com/ From the KVM point of view the patches look good (though I wouldn't mind if Nicholas took a look at the ppc part). Jason's comment on the MMU notifier side are promising as well. Can you send v3 with Oliver's comments addressed? Thanks, Paolo