On 2020/7/18 上午12:12, Alex Williamson wrote:
On Thu, 16 Jul 2020 16:32:30 +0800 Yan Zhao <yan.y.zhao@intel.com> wrote:
On Thu, Jul 16, 2020 at 12:16:26PM +0800, Jason Wang wrote:
On 2020/7/14 上午7:29, Yan Zhao wrote:
hi folks, we are defining a device migration compatibility interface that helps upper layer stack like openstack/ovirt/libvirt to check if two devices are live migration compatible. The "devices" here could be MDEVs, physical devices, or hybrid of the two. e.g. we could use it to check whether - a src MDEV can migrate to a target MDEV, - a src VF in SRIOV can migrate to a target VF in SRIOV, - a src MDEV can migration to a target VF in SRIOV. (e.g. SIOV/SRIOV backward compatibility case)
The upper layer stack could use this interface as the last step to check if one device is able to migrate to another device before triggering a real live migration procedure. we are not sure if this interface is of value or help to you. please don't hesitate to drop your valuable comments.
(1) interface definition The interface is defined in below way:
__ userspace /\ \ / \write / read \ ________/__________ ___\|/_____________ | migration_version | | migration_version |-->check migration --------------------- --------------------- compatibility device A device B
a device attribute named migration_version is defined under each device's sysfs node. e.g. (/sys/bus/pci/devices/0000\:00\:02.0/$mdev_UUID/migration_version).
Are you aware of the devlink based device management interface that is proposed upstream? I think it has many advantages over sysfs, do you consider to switch to that?
Advantages, such as?
My understanding for devlink(netlink) over sysfs (some are mentioned at the time of vDPA sysfs mgmt API discussion) are: i tought netlink was used more a as a configuration protocoal to qurry and confire nic and i guess other devices in its devlink form requireint a tool to be witten that can speak the protocal to interact with.
On Mon, 2020-07-20 at 11:41 +0800, Jason Wang wrote: the primary advantate of sysfs is that everything is just a file. there are no addtional depleenceis needed and unlike netlink there are not interoperatblity issues in a coanitnerised env. if you are using diffrenet version of libc and gcc in the contaienr vs the host my understanding is tools like ethtool from ubuntu deployed in a container on a centos host can have issue communicating with the host kernel. if its jsut a file unless the format the data is returnin in chagnes or the layout of sysfs changes its compatiable regardless of what you use to read it.
- existing users (NIC, crypto, SCSI, ib), mature and stable - much better error reporting (ext_ack other than string or errno) - namespace aware - do not couple with kobject
Thanks