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Wed, 13 May 2020 13:48:59 +0000 (UTC) Date: Wed, 13 May 2020 14:48:56 +0100 From: "Dr. David Alan Gilbert" To: Daniel =?iso-8859-1?Q?P=2E_Berrang=E9?= Subject: Re: [PATCH 0/5] Introduce 'yank' oob qmp command to recover from hanging qemu Message-ID: <20200513134856.GK3225@work-vm> References: <20200511120718.GD2811@work-vm> <20200511121714.GL1135885@redhat.com> <20200511154645.GI2811@work-vm> <20200512113206.62836e44@luklap> <20200512094337.GK1191162@redhat.com> <20200513103245.GD6202@linux.fritz.box> <20200513105359.GF3225@work-vm> <20200513111320.GE6202@linux.fritz.box> <20200513125624.GJ3225@work-vm> <20200513130849.GD1253949@redhat.com> MIME-Version: 1.0 In-Reply-To: <20200513130849.GD1253949@redhat.com> User-Agent: Mutt/1.13.4 (2020-02-15) X-Scanned-By: MIMEDefang 2.79 on 10.5.11.12 X-Mimecast-Spam-Score: 0 X-Mimecast-Originator: redhat.com Content-Type: text/plain; charset=iso-8859-1 Content-Transfer-Encoding: 8bit Content-Disposition: inline Received-SPF: pass client-ip=207.211.31.120; envelope-from=dgilbert@redhat.com; helo=us-smtp-1.mimecast.com X-detected-operating-system: by eggs.gnu.org: First seen = 2020/05/13 03:05:18 X-ACL-Warn: Detected OS = Linux 2.2.x-3.x [generic] [fuzzy] X-Spam_score_int: -20 X-Spam_score: -2.1 X-Spam_bar: -- X-Spam_report: (-2.1 / 5.0 requ) BAYES_00=-1.9, DKIMWL_WL_HIGH=0.001, DKIM_SIGNED=0.1, DKIM_VALID=-0.1, DKIM_VALID_AU=-0.1, DKIM_VALID_EF=-0.1, RCVD_IN_DNSWL_NONE=-0.0001, RCVD_IN_MSPIKE_H2=-0.001, SPF_PASS=-0.001, T_HK_NAME_DR=0.01, URIBL_BLOCKED=0.001 autolearn=_AUTOLEARN X-Spam_action: no action X-BeenThere: qemu-devel@nongnu.org X-Mailman-Version: 2.1.23 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Cc: Kevin Wolf , Lukas Straub , qemu-block , Juan Quintela , qemu-devel , Max Reitz , =?iso-8859-1?Q?Marc-Andr=E9?= Lureau , Paolo Bonzini Errors-To: qemu-devel-bounces+qemu-devel=archiver.kernel.org@nongnu.org Sender: "Qemu-devel" * Daniel P. Berrangé (berrange@redhat.com) wrote: > On Wed, May 13, 2020 at 01:56:24PM +0100, Dr. David Alan Gilbert wrote: > > * Kevin Wolf (kwolf@redhat.com) wrote: > > > I guess it would be nice to have a single namespace for everything in > > > QEMU, but the reality is that we have a few separate ones. As long as we > > > consistently add a prefix that identifies the namespace in question, I > > > think that would work. > > > > > This means that if we're using node-name to identify the NBD connection, > > > the namespace should be 'block' rather than 'nbd'. > > > > > > One more thing to consider is, what if a single object has multiple > > > connections? In the case of node-names, we have a limited set of allowed > > > characters, so we can use one of the remaining characters as a separator > > > and then suffix a counter. In other places, the identifier isn't > > > restricted, so suffixing doesn't work. Maybe prefixing does, but it > > > would have to be there from the beginning then. > > > > Yeh I worry about whether on nbd if you can have multiple nbd > > connections to one block device. > > The kernel NBD driver now supports multiple parallel connections. > QEMU hasn't implemented this in its NBD code yet, but I certainly > see that being in scope for future. It's not parallel for performance that worries me, it's more about separateq connections for separate uses - e.g. if we're serving the same read-only disk to multiple separate things. Dave > > Regards, > Daniel > -- > |: https://berrange.com -o- https://www.flickr.com/photos/dberrange :| > |: https://libvirt.org -o- https://fstop138.berrange.com :| > |: https://entangle-photo.org -o- https://www.instagram.com/dberrange :| -- Dr. David Alan Gilbert / dgilbert@redhat.com / Manchester, UK