[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index]
Re: device compatibility interface for live migration with assigned devi
From: |
Sean Mooney |
Subject: |
Re: device compatibility interface for live migration with assigned devices |
Date: |
Mon, 20 Jul 2020 11:39:14 +0100 |
On Mon, 2020-07-20 at 11:41 +0800, Jason Wang wrote:
> 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.
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
>
Re: device compatibility interface for live migration with assigned devices, Jason Wang, 2020/07/16
Re: device compatibility interface for live migration with assigned devices, Yan Zhao, 2020/07/20
Re: device compatibility interface for live migration with assigned devices, Yan Zhao, 2020/07/27
Re: device compatibility interface for live migration with assigned devices, Alex Williamson, 2020/07/27
Re: device compatibility interface for live migration with assigned devices, Yan Zhao, 2020/07/29
Re: device compatibility interface for live migration with assigned devices, Sean Mooney, 2020/07/29
Re: device compatibility interface for live migration with assigned devices, Alex Williamson, 2020/07/29
Re: device compatibility interface for live migration with assigned devices, Yan Zhao, 2020/07/29
Re: device compatibility interface for live migration with assigned devices, Sean Mooney, 2020/07/30
Re: device compatibility interface for live migration with assigned devices, Alex Williamson, 2020/07/30