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([2001:b07:6468:f312:c8dd:75d4:99ab:290a]) by smtp.gmail.com with ESMTPSA id r18sm6837910wro.62.2021.06.11.05.14.10 (version=TLS1_3 cipher=TLS_AES_128_GCM_SHA256 bits=128/128); Fri, 11 Jun 2021 05:14:11 -0700 (PDT) Subject: Re: [PATCH v7 1/4] KVM: stats: Separate generic stats from architecture specific ones To: Christian Borntraeger , Jing Zhang , KVM , KVMARM , LinuxMIPS , KVMPPC , LinuxS390 , Linuxkselftest , Marc Zyngier , James Morse , Julien Thierry , Suzuki K Poulose , Will Deacon , Huacai Chen , Aleksandar Markovic , Thomas Bogendoerfer , Paul Mackerras , Janosch Frank , David Hildenbrand , Cornelia Huck , Claudio Imbrenda , Sean Christopherson , Vitaly Kuznetsov , Jim Mattson , Peter Shier , Oliver Upton , David Rientjes , Emanuele Giuseppe Esposito , David Matlack , Ricardo Koller , Krish Sadhukhan References: <20210603211426.790093-1-jingzhangos@google.com> <20210603211426.790093-2-jingzhangos@google.com> <03f3fa03-6f61-7864-4867-3dc332a9d6f3@de.ibm.com> <050e9d8e-278d-278c-13f7-ea0b39d13fbe@de.ibm.com> From: Paolo Bonzini Message-ID: <8dd7259c-d0f6-6816-178f-ab0f0b486955@redhat.com> Date: Fri, 11 Jun 2021 14:14:09 +0200 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:78.0) Gecko/20100101 Thunderbird/78.10.1 MIME-Version: 1.0 In-Reply-To: <050e9d8e-278d-278c-13f7-ea0b39d13fbe@de.ibm.com> Content-Type: text/plain; charset=utf-8; format=flowed Content-Language: en-US Content-Transfer-Encoding: 7bit Precedence: bulk List-ID: X-Mailing-List: linux-kselftest@vger.kernel.org On 11/06/21 14:08, Christian Borntraeger wrote: >> >> I always interpreted it as "number of times the KVM page table >> management code needed other CPUs to learn about new page tables". >> Whether the broadcast is done in software or hardware shouldn't >> matter; either way I suppose there is still some traffic on the bus >> involved. > > > My point is that KVM page table management on s390x completely > piggy-backs on the qemu address space page table management from common > code for the last level. > And due to the way we handle page tables we also do not teach "other > CPUs". We always teach the whole system with things like IPTE. But that just means that you'll have fewer KVM-exclusive and thus nicer numbers than x86 or ARM. :) It still makes sense to count gmap_flush_tlb calls. Paolo