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([2001:b07:6468:f312:c8dd:75d4:99ab:290a]) by smtp.gmail.com with ESMTPSA id e18sm3537900ejh.64.2021.06.17.04.19.51 (version=TLS1_3 cipher=TLS_AES_128_GCM_SHA256 bits=128/128); Thu, 17 Jun 2021 04:19:52 -0700 (PDT) Subject: Re: [PATCH v10 3/5] KVM: stats: Add documentation for binary statistics interface To: Greg KH , Jing Zhang Cc: 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 , Christian Borntraeger , 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 , Fuad Tabba References: <20210617044146.2667540-1-jingzhangos@google.com> <20210617044146.2667540-4-jingzhangos@google.com> From: Paolo Bonzini Message-ID: Date: Thu, 17 Jun 2021 13:19:50 +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: 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-s390@vger.kernel.org On 17/06/21 08:07, Greg KH wrote: >> The statistics data itself could be read out by userspace telemetry >> periodically without any extra parsing or setup effort. > Do you have a pointer to userspace code that can do such a thing that > others can use? We do not like adding apis to the kernel without at > least seeing the user of those apis, especially for complex things like > this. > > Ideally you would include some library code in the kernel tree itself > that everyone can use for this for their own programs. You have > provided a test which is great, but how do we know it works for "real" > usages? I am pretty sure that Google is using this internally, but we are also going to work on QEMU and Libvirt support for this. As for the rest, thanks for the review---I'll let Jing act on it and only add my own remarks in a couple places. Paolo