[ovs-dev] [PATCH] dpdk: announce deprecation of vhost-user server ports

Darrell Ball dball at vmware.com
Thu Jun 8 18:13:15 UTC 2017



On 6/8/17, 6:40 AM, "Aaron Conole" <aconole at redhat.com> wrote:

    Hi Darrell,
    
    Thanks so much for the review!  Comments below.
    
    Darrell Ball <dball at vmware.com> writes:
    
    > On 6/7/17, 3:46 PM, "Aaron Conole" <aconole at redhat.com> wrote:
    >
    >     Since vhost-user server mode ports are the preferred mechanism for
    >     interconnecting Open vSwitch with VMs when using DPDK, and since there
    >     are currently no known use cases for vhost-user server mode ports apart
    >     from version incompatibilities with QEMU, announce that server mode ports
    >     are considered deprecated and will be removed in a future release.
    >     
    >     Cc: Ciara Loftus <ciara.loftus at intel.com>
    >     Cc: Kevin Traynor <ktraynor at redhat.com>
    >     Suggested-by: Darrell Ball <dball at vmware.com>
    >     Signed-off-by: Aaron Conole <aconole at redhat.com>
    >     ---
    >      Documentation/topics/dpdk/vhost-user.rst | 24 ++++++++++++++++--------
    >      NEWS                                     |  2 ++
    >      lib/netdev-dpdk.c                        |  2 ++
    >      3 files changed, 20 insertions(+), 8 deletions(-)
    >     
    >     diff --git a/Documentation/topics/dpdk/vhost-user.rst b/Documentation/topics/dpdk/vhost-user.rst
    >     index a1c19fd..9d36cf2 100644
    >     --- a/Documentation/topics/dpdk/vhost-user.rst
    >     +++ b/Documentation/topics/dpdk/vhost-user.rst
    >     @@ -32,13 +32,19 @@ documentation`_ on same.
    >      Quick Example
    >      -------------
    >      
    >     -This example demonstrates how to add two ``dpdkvhostuser`` ports to an existing
    >     -bridge called ``br0``::
    >     +This example demonstrates how to add two ``dpdkvhostuserclient`` ports to an
    >     +existing bridge called ``br0``::
    >      
    >     -    $ ovs-vsctl add-port br0 dpdkvhostuser0 \
    >     -        -- set Interface dpdkvhostuser0 type=dpdkvhostuser
    >     -    $ ovs-vsctl add-port br0 dpdkvhostuser1 \
    >     -        -- set Interface dpdkvhostuser1 type=dpdkvhostuser
    >     +    $ ovs-vsctl add-port br0 dpdkvhostclient0 \
    >     +        -- set Interface dpdkvhostclient0 type=dpdkvhostuserclient \
    >     +           options:vhost-server-path=/tmp/dpdkvhostclient0
    >     +    $ ovs-vsctl add-port br0 dpdkvhostclient1 \
    >     +        -- set Interface dpdkvhostclient1 type=dpdkvhostuserclient \
    >     +           options:vhost-server-path=/tmp/dpdkvhostclient1
    >     +
    >     +For the above examples to work, an appropriate server socket must be created
    >     +at the paths specified (``/tmp/dpdkvhostclient0`` and
    >     +``/tmp/dpdkvhostclient0``).
    >      
    >      vhost-user vs. vhost-user-client
    >      --------------------------------
    >     @@ -59,7 +65,8 @@ means if OVS dies, all VMs **must** be restarted. On the other hand, for
    >      vhost-user-client ports, OVS acts as the client and QEMU the server. This means
    >      OVS can die and be restarted without issue, and it is also possible to restart
    >      an instance itself. For this reason, vhost-user-client ports are the preferred
    >     -type for most use cases.
    >     +type for most use cases.  Ports of type vhost-user are currently deprecated and
    >     +will be removed in a future release.
    >
    > type for all known use cases; the only limitation is that vhost-user client mode ports
    > require QEMU version 2.7.  Ports of type vhost-user are currently deprecated and
    > will be removed in a future release.
    
    Will update with this verbiage.  Thanks.
    
    >      .. _dpdk-vhost-user:
    >      
    >     @@ -68,7 +75,8 @@ vhost-user
    >      
    >      .. important::
    >      
    >     -   Use of vhost-user ports requires QEMU >= 2.2
    >     +   Use of vhost-user ports requires QEMU >= 2.2;  vhost-user ports are
    >     +   *deprecated*.
    >      
    >      To use vhost-user ports, you must first add said ports to the switch. DPDK
    >      vhost-user ports can have arbitrary names with the exception of forward and
    >     diff --git a/NEWS b/NEWS
    >     index 82004c8..b81d033 100644
    >     --- a/NEWS
    >     +++ b/NEWS
    >     @@ -16,6 +16,8 @@ Post-v2.7.0
    >             Log level can be changed in a usual OVS way using
    >             'ovs-appctl vlog' commands for 'dpdk' module. Lower bound
    >             still can be configured via extra arguments for DPDK EAL.
    >     +     * dpdkvhostuser ports are marked as deprecated.  They will be removed
    >     +       in an upcoming release.
    >         - IPFIX now provides additional counters:
    >           * Total counters since metering process startup.
    >           * Per-flow TCP flag counters.
    >     diff --git a/lib/netdev-dpdk.c b/lib/netdev-dpdk.c
    >     index b770b70..9ab4aeb 100644
    >     --- a/lib/netdev-dpdk.c
    >     +++ b/lib/netdev-dpdk.c
    >     @@ -966,6 +966,8 @@ netdev_dpdk_vhost_construct(struct netdev *netdev)
    >          err = vhost_common_construct(netdev);
    >      
    >          ovs_mutex_unlock(&dpdk_mutex);
    >     +    VLOG_WARN_ONCE("dpdkvhostuser ports are considered deprecated;  "
    >     +                   "please migrate to dpdkvhostuserclient ports.");
    >
    > I think we can:
    > 1) Print the socket name and port name
    > 2) I am not sure ‘_ONCE’ is required; do you really think the log will have that many instances.
    
    My idea to not print the socket / port name is because I figure there
    would be cases that users have many VMs, do an upgrade, and see the log
    spewed over and over.  Maybe that's a good thing though - not sure.
    
    If you consider a deployment with 100 VMs, that means this will pop up
    100 times.  Even more, in deployments where they are using orchestration
    software, or a cluster management solution, I figure those systems may
    still be using the old style dpdkvhostuser ports, and again didn't want
    to print it for every start of a VM - especially when there isn't
    anything the user could do about it.
    
    If you think there's a strong value in warning on every start, and
    including the details of the port, I'll do that.  I'm not married to
    this particular code ;)

I was thinking more like 20 times would be the high number in most cases, but 100 is fine in rare cases.

This should be hard to ignore (maybe even a little annoying) for the
ultimate benefit of the user experience.



    
    -Aaron
    



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