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From: Paolo Bonzini <pbonzini@redhat.com>
To: Leon Romanovsky <leon@kernel.org>, Jing Zhang <jingzhangos@google.com>
Cc: KVM <kvm@vger.kernel.org>, KVMARM <kvmarm@lists.cs.columbia.edu>,
	LinuxMIPS <linux-mips@vger.kernel.org>,
	KVMPPC <kvm-ppc@vger.kernel.org>,
	LinuxS390 <linux-s390@vger.kernel.org>,
	Linuxkselftest <linux-kselftest@vger.kernel.org>,
	Marc Zyngier <maz@kernel.org>, James Morse <james.morse@arm.com>,
	Julien Thierry <julien.thierry.kdev@gmail.com>,
	Suzuki K Poulose <suzuki.poulose@arm.com>,
	Will Deacon <will@kernel.org>,
	Huacai Chen <chenhuacai@kernel.org>,
	Aleksandar Markovic <aleksandar.qemu.devel@gmail.com>,
	Thomas Bogendoerfer <tsbogend@alpha.franken.de>,
	Paul Mackerras <paulus@ozlabs.org>,
	Christian Borntraeger <borntraeger@de.ibm.com>,
	Janosch Frank <frankja@linux.ibm.com>,
	David Hildenbrand <david@redhat.com>,
	Cornelia Huck <cohuck@redhat.com>,
	Claudio Imbrenda <imbrenda@linux.ibm.com>,
	Sean Christopherson <seanjc@google.com>,
	Vitaly Kuznetsov <vkuznets@redhat.com>,
	Jim Mattson <jmattson@google.com>,
	Peter Shier <pshier@google.com>, Oliver Upton <oupton@google.com>,
	David Rientjes <rientjes@google.com>,
	Emanuele Giuseppe Esposito <eesposit@redhat.com>,
	David Matlack <dmatlack@google.com>,
	Ricardo Koller <ricarkol@google.com>,
	Krish Sadhukhan <krish.sadhukhan@oracle.com>,
	Fuad Tabba <tabba@google.com>
Subject: Re: [PATCH v9 0/5] KVM statistics data fd-based binary interface
Date: Tue, 15 Jun 2021 09:06:43 +0200	[thread overview]
Message-ID: <15875c41-e1e7-3bf2-a85c-21384684d279@redhat.com> (raw)
In-Reply-To: <YMg5xPbmK3myjIX8@unreal>

On 15/06/21 07:25, Leon Romanovsky wrote:
> Sorry for my naive questions, but how does telemetry get statistics
> for hypervisors? Why is KVM different from hypervisors or NIC's statistics
> or any other high speed devices (RDMA) that generate tons of data?

Right now, the only way is debugfs but it's slow, and it's disabled when 
using lockdown mode; this series is a way to fix this.

I sense that there is another question in there; are you wondering if 
another mechanism should be used, for example netlink?  The main issue 
there is how to identify a VM, since KVM file descriptors don't have a 
name.  Using a pid works (sort of) for debugfs, but pids are not 
appropriate for a stable API.  Using a file descriptor as in this series 
requires collaboration from the userspace program; howver, once the file 
descriptor has been transmitted via SCM_RIGHTS, telemetry can read it 
forever without further IPC, and there is proper privilege separation.

Paolo


  reply	other threads:[~2021-06-15  7:06 UTC|newest]

Thread overview: 22+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2021-06-14 21:21 [PATCH v9 0/5] KVM statistics data fd-based binary interface Jing Zhang
2021-06-14 21:21 ` [PATCH v9 1/5] KVM: stats: Separate generic stats from architecture specific ones Jing Zhang
2021-06-14 21:21 ` [PATCH v9 2/5] KVM: stats: Add fd-based API to read binary stats data Jing Zhang
2021-06-16 17:12   ` Paolo Bonzini
2021-06-16 18:04     ` Jing Zhang
2021-06-14 21:21 ` [PATCH v9 3/5] KVM: stats: Add documentation for statistics data binary interface Jing Zhang
2021-06-16 15:21   ` Greg KH
2021-06-16 16:59     ` Paolo Bonzini
2021-06-16 18:18       ` Greg KH
2021-06-16 19:45         ` Paolo Bonzini
2021-06-14 21:21 ` [PATCH v9 4/5] KVM: selftests: Add selftest for KVM " Jing Zhang
2021-06-15  8:03   ` Fuad Tabba
2021-06-16 21:35     ` Jing Zhang
2021-06-14 21:21 ` [PATCH v9 5/5] KVM: stats: Remove code duplication for binary and debugfs stats Jing Zhang
2021-06-15  5:25 ` [PATCH v9 0/5] KVM statistics data fd-based binary interface Leon Romanovsky
2021-06-15  7:06   ` Paolo Bonzini [this message]
2021-06-15  7:53     ` Leon Romanovsky
2021-06-15 11:03       ` Paolo Bonzini
2021-06-15 13:34         ` Leon Romanovsky
2021-06-15  8:37 ` Enrico Weigelt, metux IT consult
2021-06-15  9:21   ` Greg KH
2021-06-15 11:31   ` Paolo Bonzini

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