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Date:   Fri, 9 Jun 2023 11:07:55 +0200
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To:     Yu Zhao <yuzhao@google.com>,
        Andrew Morton <akpm@linux-foundation.org>
Cc:     Alistair Popple <apopple@nvidia.com>,
        Anup Patel <anup@brainfault.org>,
        Ben Gardon <bgardon@google.com>,
        Borislav Petkov <bp@alien8.de>,
        Catalin Marinas <catalin.marinas@arm.com>,
        Chao Peng <chao.p.peng@linux.intel.com>,
        Christophe Leroy <christophe.leroy@csgroup.eu>,
        Dave Hansen <dave.hansen@linux.intel.com>,
        Fabiano Rosas <farosas@linux.ibm.com>,
        Gaosheng Cui <cuigaosheng1@huawei.com>,
        Gavin Shan <gshan@redhat.com>,
        "H. Peter Anvin" <hpa@zytor.com>, Ingo Molnar <mingo@redhat.com>,
        James Morse <james.morse@arm.com>,
        "Jason A. Donenfeld" <Jason@zx2c4.com>,
        Jason Gunthorpe <jgg@ziepe.ca>,
        Jonathan Corbet <corbet@lwn.net>,
        Marc Zyngier <maz@kernel.org>,
        Masami Hiramatsu <mhiramat@kernel.org>,
        Michael Ellerman <mpe@ellerman.id.au>,
        Michael Larabel <michael@michaellarabel.com>,
        Mike Rapoport <rppt@kernel.org>,
        Nicholas Piggin <npiggin@gmail.com>,
        Oliver Upton <oliver.upton@linux.dev>,
        Paul Mackerras <paulus@ozlabs.org>,
        Peter Xu <peterx@redhat.com>,
        Sean Christopherson <seanjc@google.com>,
        Steven Rostedt <rostedt@goodmis.org>,
        Suzuki K Poulose <suzuki.poulose@arm.com>,
        Thomas Gleixner <tglx@linutronix.de>,
        Thomas Huth <thuth@redhat.com>, Will Deacon <will@kernel.org>,
        Zenghui Yu <yuzenghui@huawei.com>, 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 <pbonzini@redhat.com>
Subject: Re: [PATCH mm-unstable v2 00/10] mm/kvm: locklessly clear the
 accessed bit
In-Reply-To: <20230526234435.662652-1-yuzhao@google.com>
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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