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

Stokes, Ian ian.stokes at intel.com
Tue Sep 29 16:35:07 UTC 2020


> On 9/10/20 8:11 PM, Ilya Maximets 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."
> 
> Yes, Ilya is right.
> 
> With above fixed, the patch looks good to me:
> Acked-by: Maxime Coquelin <maxime.coquelin at redhat.com>

Thanks Maxime, as flagged to Ilya I can apply this on commit before applying.

Regards
Ian
> 
> Thanks,
> Maxime
> 
> > Best regards, Ilya Maximets.
> > _______________________________________________
> > dev mailing list
> > dev at openvswitch.org
> > https://mail.openvswitch.org/mailman/listinfo/ovs-dev
> >



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