[ovs-dev] [PATCH v2 1/1] DPDK: Remove support for vhost-user zero-copy.

[Stokes, Ian]

> On 29/09/2020 17:44, Ilya Maximets wrote:
> > On 9/29/20 6:33 PM, Stokes, Ian wrote:
> >>> On 9/10/20 7:30 PM, Ian Stokes wrote:
> >>>> Support for vhost-user dequeue zero-copy was deprecated in OVS 2.14
> >>> with
> >>>> the aim of removing it for OVS 2.15.
> >>>>
> >>>> OVS only supports zero copy for vhost client mode, as such it will cease
> >>>> to function due to DPDK commit [1]
> >>>>
> >>>> Also DPDK is set to remove zero-copy functionality in DPDK 20.11 as
> >>>> referenced by commit [2]
> >>>>
> >>>> As such remove support from OVS.
> >>>>
> >>>> [1] 715070ea10e6 ("vhost: prevent zero-copy with incompatible client
> >>> mode")
> >>>> [2] d21003c9dafa ("doc: announce removal of vhost zero-copy dequeue")
> >>>>
> >>>> Signed-off-by: Ian Stokes <ian.stokes at intel.com>
> >>>>
> >>>> ---
> >>>> v1 -> v2
> >>>> * Remove reference to zero copy in vhost post copy documentation.
> >>>> * Add DPDK commits that have influenced OVS decision to remove support
> >>>>   for zero-copy.
> >>>> * Correct NEWS to reference removal rather than deprecation of zc.
> >>>> ---
> >>>>  Documentation/topics/dpdk/vhost-user.rst | 76 -------------------------------
> -
> >>>>  NEWS                                     |  2 +
> >>>>  lib/netdev-dpdk.c                        | 25 -----------
> >>>>  vswitchd/vswitch.xml                     | 11 -----
> >>>>  4 files changed, 2 insertions(+), 112 deletions(-)
> >>>>
> >>>> diff --git a/Documentation/topics/dpdk/vhost-user.rst
> >>> b/Documentation/topics/dpdk/vhost-user.rst
> >>>> index 4af738d11..3be8f8b5e 100644
> >>>> --- a/Documentation/topics/dpdk/vhost-user.rst
> >>>> +++ b/Documentation/topics/dpdk/vhost-user.rst
> >>>> @@ -339,10 +339,6 @@ The default value is ``false``.
> >>>>      migration recovery was fixed for post-copy in 3.0 and few additional
> bug
> >>>>      fixes (like userfaulfd leak) was released in 3.0.1.
> >>>>
> >>>> -    DPDK Post-copy feature requires avoiding to populate the guest
> >>> memory
> >>>> -    (application must not call mlock* syscall). So enabling mlockall and
> >>>> -    dequeue zero-copy features is mis-compatible with post-copy feature.
> >>>
> >>> The part about mlockall is still valid, only zero-copy related words should be
> >>> removed, e.g. "So enabling mlockall is mis-compatible with post-copy
> >>> feature."
> >>
> >> Apologies for the delay Ilya, I was on PTO the last few weeks, sure will make
> think change and apply with an ACK from yourself if that’s ok?
> >
> > OK, sure.  With this change:
> > Acked-by: Ilya Maximets <i.maximets at ovn.org>
> >
> 
> +1
> 
> Acked-by: Kevin Traynor <ktraynor at redhat.com>

Thanks all for the reviews and input, I've made change above and applied to master.

Regards
Ian