On 6/4/17, 9:15 AM, "Aaron Conole" <[email protected]> wrote:
Darrell Ball <[email protected]> writes:
> On 5/26/17, 7:12 AM, "[email protected] on behalf of
Stephen Finucane" <[email protected] on behalf of
[email protected]> wrote:
>
> Apparently dpdkvhostuser interfaces are inferior to
dpdkvhostuserclient.
> Explain why.
>
> Signed-off-by: Stephen Finucane <[email protected]>
> Cc: Ciara Loftus <[email protected]>
> Cc: Kevin Traynor <[email protected]>
> ---
> I'd like to note what happens to traffic when OVS or a VM is restarted
> for both port types. If someone knows the answer to this, please feel
> free to take ownership of that patch/ask me for a v2.
> ---
> Documentation/topics/dpdk/vhost-user.rst | 8 ++++++--
> 1 file changed, 6 insertions(+), 2 deletions(-)
>
> diff --git a/Documentation/topics/dpdk/vhost-user.rst
b/Documentation/topics/dpdk/vhost-user.rst
> index ba22684..2e2396b 100644
> --- a/Documentation/topics/dpdk/vhost-user.rst
> +++ b/Documentation/topics/dpdk/vhost-user.rst
> @@ -54,8 +54,12 @@ vHost User sockets, and the client connects to the
server. Depending on which
> port type you use, ``dpdkvhostuser`` or ``dpdkvhostuserclient``, a
different
> configuration of the client-server model is used.
>
> -For vhost-user ports, Open vSwitch acts as the server and QEMU the
client. For
> -vhost-user-client ports, Open vSwitch acts as the client and QEMU
the server.
> +For vhost-user ports, Open vSwitch acts as the server and QEMU the
client. This
> +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.”
>
> Restart a VM instance ?; if so, it seems already implied.
> Or OVS instance ?
>
> For this reason, vhost-user-client ports are the preferred
> +type for most use cases.
>
> At one point, because I am helping to support OVS-DPDK, I had both
> vhostuser and vhostuserclient ports configured on our performance servers,
> because I thought I should have both, so I could support both. Then, I
realized I
> just did not want to use vhostuser ports, due to the permissions/security
> issues, noticed on OVS restart.
>
> So, what are the use cases (besides self-flagellation) for using
vhostuser ports in lieu of
> vhostuserclient ports ?
At the time they were introduced, deployed versions of qemu couldn't
support the vhostuserclient mode. I'm less sure what the state of that
world looks like today. I know that RHEL 7.3 doesn't ship a QEMU that
supports client-mode ports.
I understand about the qemu version requirements; I really wanted to make sure
that there were no specific use cases for server mode, per this patch text.
Do you know if there are any issues with RHEL 7.3 supporting QEMU 2.7 ?
> If the answer is none, can we deprecate them in OVS 2.8 (update NEWS etc)
and
> remove them in OVS 2.9 ?
I'm all for deprecating them as long as the major vendors (RH, Debian,
SUSE) support the newer QEMU. 2.9 may be too aggressive for removal -
perhaps the release after? Just to be sure there is a path to migration
for existing users.
Agreed; ideally, qemu should be upgradable to 2.7 on recent versions of
common/important distros such RHEL/centos, SLES and debian.
Many people have a national holiday today, so let us see when they get back.
If we can deprecate, then:
1) We might deprecate now and say in an upcoming release, vhostuserserver port
code
will be removed.
2) We can add a log warning to that effect on configuration.
3) We can add text here to suggest upgrading to qemu 2.7 if at all possible
and using client mode. qemu 2.9 is out, upgrade to 2.7 should be possible in
many (most ?) cases, for those
serious about using ovs-dpdk with VM connectivity.
Maybe I'm off my rocker, though.
> .. _dpdk-vhost-user:
>
> --
> 2.9.4
>
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