RE: [RFC 16/16] lpfc: vmid: Introducing vmid in io path.

Muneendra Kumar M
2020-08-07T12:17:33Z

>
> Before the daemon issues the UUID and pid to the fabric interface, it
> needs to check whether the VM is in running state or not.
>
> If it the VM is in running state then only it issues the VM details.
>
> And if the cgroup's are not setup as you mentioned the interface will
> return a failure(with a proper logs) and the daemon will retry after
> some time.
>
> And this also helps us to keep track of PID to UUID mapping at daemon
> level.

>Why would that be useful? Again, the mapping of the UUID is _not_ to a
>PID, it is to a cgroup. There is no concept of a VM PID; you could
>legitimately have I/O in a separate process than say the QEMU process, and
>that I/O >process could legitimately reside in a separate blkcg than QEMU.
Agreed .
When I run ps -aef | grep <VMname > we got a pid.

ps -aef | grep mmkvm1
root 3627 1 0 04:20 ? 00:00:34 /usr/libexec/qemu-kvm -name
testmmkvm1 -S

And I was talking about at the below one PIDS(3627) .And with the help of
these PIDS I was able to reach blkcg.
Correct me if iam going in a wrong direction.
And even when I run the below command it pointed me to the same pid.
cat
/sys/fs/cgroup/blkio/machine.slice/machine-qemu\\x2d7\\x2dtestmmkvm1.scope/tasks
3627 -->/usr/libexec/qemu-kvm -name testmmkvm1
3655 --> [kvm-nx-lpage-re]
3658--> vhost-3627

And I was talking about the above PIDS(3627) to be passed to the interface
along with UUID.

>There is no need for any daemon, and I'm not even sure which daemon would
>be handling this. App identifier should be purely a kernel concept with no
>userspace state.
Agreed App identifier is a pure kernel concept.
And the user can only provide the info what needs to be filled in it using
an interface.
Iam talking about FC transport daemon.
One of the feature of this daemon is to track all the running VM's and push
the appid information to the blk cgroup via the interface provided by the
fabric
And this feature is under development.

Paolo