On 22 Apr 2025, at 17:46, Simon Horman wrote:
> Rework the "I just upgraded and I see a performance drop. Why?"
> section to cover both earlier releases where the OOT module
> was recommended and the current recommendation to use the
> upstream Linux module.
>
> Signed-off-by: Simon Horman <ho...@ovn.org>
> ---
> Perhaps we could consider dropping references to old
> versions where the OOT kernel module was present entirely?
There is quite a lot of history in this section. I would not mind dropping this
(entire Q(uestion):), others?
> ---
> Documentation/faq/issues.rst | 20 +++++++++++++++-----
> 1 file changed, 15 insertions(+), 5 deletions(-)
>
> diff --git a/Documentation/faq/issues.rst b/Documentation/faq/issues.rst
> index d736d4feceff..bffad13950d6 100644
> --- a/Documentation/faq/issues.rst
> +++ b/Documentation/faq/issues.rst
> @@ -407,9 +407,9 @@ keep changing internal ports MTU?
>
> Q: I just upgraded and I see a performance drop. Why?
>
> - A: The OVS kernel datapath may have been updated to a newer version than
> - the OVS userspace components. Sometimes new versions of OVS kernel
> module
> - add functionality that is backwards compatible with older userspace
> + A: The OVS kernel datapath may have been updated to a new version without
> + updating OVS userspace components. Sometimes new versions of OVS kernel
> + module add functionality that is backwards compatible with older
> userspace
> components but may cause a drop in performance with them. Especially,
> if a
> kernel module from OVS 2.1 or newer is paired with OVS userspace 1.10 or
> older, there will be a performance drop for TCP traffic.
> @@ -417,8 +417,18 @@ Q: I just upgraded and I see a performance drop. Why?
> Updating the OVS userspace components to the latest released version
> should
> fix the performance degradation.
>
> - To get the best possible performance and functionality, it is recommended
> - to pair the same versions of the kernel module and OVS userspace.
> + The OVS kernel modules has been distributed with the upstream Linux
> kernel
> + since Linux 3.3. As of OVS 2.15 the use of the kernel module distributed
> + with OVS is deprecated in favour of the kernel module distributed with
> the
> + upstream Linux kernel. And as of OVS 3.0 the kernel module is no longer
> + part of the OVS distribution.
> +
> + Accordingly, for OVS 2.15 and newer, to get the best possible performance
> + and functionality it is recommended to pair the latest released version
> of
> + OVS with the latest released version of the Linux kernel. While, for
> + releases of OVS prior to 2.15, is recommended to pair the same versions
> of
> + the kernel module and OVS userspace.
> +
>
> Q: I can't unload the openvswitch kernel module. Why?
>
>
> --
> 2.47.2
>
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