[ovs-dev] [PATCH v2 1/1] DPDK: Remove support for vhost-user zero-copy.
Ilya Maximets
i.maximets at ovn.org
Thu Sep 10 18:11:52 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."
Best regards, Ilya Maximets.
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