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Tsirkin" To: Christian Schoenebeck Subject: Re: [PATCH v10 0/8] hmp,qmp: Add commands to introspect virtio devices Message-ID: <20211206165617-mutt-send-email-mst@kernel.org> References: <1638794606-19631-1-git-send-email-jonah.palmer@oracle.com> <2322952.dU7V5S69UE@silver> <819408538.haW0C61HAu@silver> MIME-Version: 1.0 In-Reply-To: <819408538.haW0C61HAu@silver> Authentication-Results: relay.mimecast.com; auth=pass smtp.auth=CUSA124A263 smtp.mailfrom=mst@redhat.com X-Mimecast-Spam-Score: 0 X-Mimecast-Originator: redhat.com Content-Type: text/plain; charset=us-ascii Content-Disposition: inline Received-SPF: pass client-ip=170.10.129.124; envelope-from=mst@redhat.com; helo=us-smtp-delivery-124.mimecast.com X-Spam_score_int: -33 X-Spam_score: -3.4 X-Spam_bar: --- X-Spam_report: (-3.4 / 5.0 requ) BAYES_00=-1.9, DKIMWL_WL_HIGH=-0.619, DKIM_SIGNED=0.1, DKIM_VALID=-0.1, DKIM_VALID_AU=-0.1, DKIM_VALID_EF=-0.1, RCVD_IN_DNSWL_LOW=-0.7, RCVD_IN_MSPIKE_H3=0.001, RCVD_IN_MSPIKE_WL=0.001, SPF_HELO_NONE=0.001, SPF_PASS=-0.001 autolearn=unavailable autolearn_force=no X-Spam_action: no action X-BeenThere: qemu-devel@nongnu.org X-Mailman-Version: 2.1.29 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Cc: david@redhat.com, qemu-devel@nongnu.org, kraxel@redhat.com, si-wei.liu@oracle.com, joao.m.martins@oracle.com, eblake@redhat.com, qemu-block@nongnu.org, armbru@redhat.com, arei.gonglei@huawei.com, marcandre.lureau@redhat.com, Jonah Palmer , lvivier@redhat.com, thuth@redhat.com, michael.roth@amd.com, groug@kaod.org, dgilbert@redhat.com, eric.auger@redhat.com, stefanha@redhat.com, boris.ostrovsky@oracle.com, kwolf@redhat.com, mathieu.poirier@linaro.org, raphael.norwitz@nutanix.com, pbonzini@redhat.com Errors-To: qemu-devel-bounces+qemu-devel=archiver.kernel.org@nongnu.org Sender: "Qemu-devel" On Mon, Dec 06, 2021 at 07:13:49PM +0100, Christian Schoenebeck wrote: > On Montag, 6. Dezember 2021 17:09:45 CET Jonah Palmer wrote: > > On 12/6/21 08:50, Christian Schoenebeck wrote: > > > On Montag, 6. Dezember 2021 13:43:18 CET Jonah Palmer wrote: > > >> This series introduces new QMP/HMP commands to dump the status of a > > >> virtio device at different levels. > > >> > > >> [Jonah: Rebasing previous patchset from Nov. 10 (v9). Original patches > > >> > > >> are by Laurent Vivier from May 2020. > > >> > > >> Rebase from v9 to v10 includes reformatting virtio.json examples and > > >> command structures for better consistency. Also removed all enums from > > >> virtio.json and replaced their purpose with string literals. > > >> > > >> Removed @ndescs from VirtioQueueElement, as the number of descriptors > > >> can be inferred from the length of the @descs chain. > > >> > > >> Lastly, removed the examples in hmp-commands-info.hx to fix > > >> 'inconsistent > > >> literal block quoting' warning from Sphinx.] > > > > > > I have not followed the entire discussion. AFAICS this is intended to > > > monitor status information on virtio level only, like virtqueue fill > > > status, etc. > > > > > > One thing that I am looking for is monitoring device specific information > > > above virtio level, e.g. certain performance numbers or statistics that > > > only make sense for the specific device. That would not fit into any of > > > these commands, right? > > > > > > Best regards, > > > Christian Schoenebeck > > > > Correct. These are just one-shot commands that dump information on virtio > > devices (including vhosts), their virtqueues, and virtqueue elements as they > > are at the time of the command. > > > > Jonah > > What I would find useful though on this virtio level: also being able to query > the maximum and average fill state of the two ring buffers of each virtqueue. > That would allow to identify performance bottlenecks. > > Best regards, > Christian Schoenebeck Adding this to vhost would need some interface work though. Also, collecting these stats isn't free or trivial, so I imagine we would need commands to enable/disable data collection. -- MST