ConnectX-6 Dx with RRSv2

[banduraj]

I’m very confused about about the state of RSS on the ConnectX-6 Dx series of cards installed in a Dell R740xd running Windows Server 20022 with Hyper-V. Everything I have read from Microsoft seems to imply that RSSv2 is enabled by default, however the docs for the driver version we’re currently using seems to imply otherwise.

Using the PowerShell command: Get-NetAdapterRss shows that RSS is enabled on our physical and virtual adapters, but it’s not clear as to what version specifically is in use.

From the NVIDIA driver docs:

Configuring the Driver Registry Keys - NVIDIA Docs

Specifically in the Performance Registry Keys:

Value: RssV2, default: 0, Enables the RSS v2 feature which improves the Receive Side Scaling by offering dynamic, per-VPort spreading of queues. It reduces the time to update the indirection table. Note: RSSv2 is only supported by NDIS 6.80 and later versions.

Value: ValidateRssV2, default: 0, Enables strict argument validation for upper layer testing. Set along with the RssV2 key to enable the RSSv2 feature.

Does the RssV2 registry value need to be set for each NIC interface to enable RSSv2 in Windows Server 2022 with Hyper-V and is the ValidateRssV2 needed as well, as the description for that value seems to imply?

Am I to assume that since these are not set, we’re actually only using RSSv1?

Thank you.

[banduraj]

I can confirm that the RssV2 registry key must exist for RSSv2 to be in use with at least this series card: ConnectX-6 Dx on Window Server 2022.

Without this key, the OID OID_GEN_RECEIVE_SCALE_PARAMETERS is used.

With this key the OID OID_GEN_RECEIVE_SCALE_PARAMETERS_V2 is used and OID OID_GEN_RSS_SET_INDIRECTION_TABLE_ENTRIES show up as well.

This was all confirmed with the command Mlx5Cmd.exe -OidStats.

Edited to add: I did not set the registry key ValidateRssV2, so it is not necessary as the document seems to imply.

[longranw]

Does the RssV2 registry value need to be set for each NIC interface to enable RSSv2 in Windows Server 2022 with Hyper-V and is the ValidateRssV2 needed as well, as the description for that value seems to imply?
– Yes, all the NIC interface needs to be set.

Am I to assume that since these are not set, we’re actually only using RSSv1?
OID_GEN_RECEIVE_SCALE_PARAMETERS - Windows drivers | Microsoft Learn
OID_GEN_RECEIVE_SCALE_PARAMETERS_V2 - Windows drivers | Microsoft Learn
I think you need to consult the Microsoft support about how these 2 options implement on your Windows 2022.(I see the document mentiond about “RSSv2 is preview only in Windows 10, version 1809”)