[ovs-dev] [PATCH v2] netdev-afxdp: Best-effort configuration of XDP mode.

[Ilya Maximets]

On 13.11.2019 1:21, William Tu wrote:
> On Thu, Nov 7, 2019 at 3:36 AM Ilya Maximets <i.maximets at ovn.org> wrote:
>>
>> Until now there was only two options for XDP mode in OVS: SKB or DRV.
>> i.e. 'generic XDP' or 'native XDP with zero-copy enabled'.
>>
>> Devices like 'veth' interfaces in Linux supports native XDP, but
>> doesn't support zero-copy mode.  This case can not be covered by
>> existing API and we have to use slower generic XDP for such devices.
>> There are few more issues, e.g. TCP is not supported in generic XDP
>> mode for veth interfaces due to kernel limitations, however it is
>> supported in native mode.
>>
>> This change introduces ability to use native XDP without zero-copy
>> along with best-effort configuration option that enabled by default.
>> In best-effort case OVS will sequentially try different modes starting
>> from the fastest one and will choose the first acceptable for current
>> interface.  This will guarantee the best possible performance.
>>
>> If user will want to choose specific mode, it's still possible by
>> setting the 'options:xdp-mode'.
>>
>> This change additionally changes the API by renaming the configuration
>> knob from 'xdpmode' to 'xdp-mode' and also renaming the modes
>> themselves to be more user-friendly.
>>
>> The full list of currently supported modes:
>>   * native-with-zerocopy - former DRV
>>   * native               - new one, DRV without zero-copy
>>   * generic              - former SKB
>>   * best-effort          - new one, chooses the best available from
>>                            3 above modes
>>
>> Since 'best-effort' is a default mode, users will not need to
>> explicitely set 'xdp-mode' in most cases.
>>
>> TCP related tests enabled back in system afxdp testsuite, because
>> 'best-effort' will choose 'native' mode for veth interfaces
>> and this mode has no issues with TCP.
>>
>> Signed-off-by: Ilya Maximets <i.maximets at ovn.org>
>> ---
> 
> I'm thinking about adding some tests case and patches depends on
> this API change. If there is no more comment, I will apply to master.

I think, it might be good to wait for some comments from Eelco.

@Eelco, do you have a plan to review the code? Do you agree with the
API update?

Best regards, Ilya Maximets.