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

Stokes, Ian ian.stokes at intel.com
Tue Sep 29 16:33:59 UTC 2020


> 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?

Regards
Ian
> 
> Best regards, Ilya Maximets.


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