Disable DDIO in Icelake servers

[SakshamAgarwal]

Hi,

We've been trying to disable DDIO on our recently purchased IceLake servers (Intel(R) Xeon(R) Platinum 8362 CPU @ 2.80GHz), but it hasn't been possible so far. Could anyone please suggest how to do it?

Here are the steps we've already tried:

1. We'd been using the steps mentioned in ddio-bench repo on GitHub (https://github.com/aliireza/ddio-bench) and on this blog post (http://janekmi.github.io/2020/06/21/ddio.html) to disable DDIO on our CascadeLake servers successfully in the past. 

The code didn’t work straight away on IceLake. So I went through the code description and it required changing the bit 7 (Use_Allocating_Flow_Wr) of the register
PERFCTRLSTS_0 (at offset 0x180 of the PCIe root address of the bus containing the NICs). Going through the new IceLake register manual, it turns out that Intel has specifically made the bits 7:6 reserved, and there is no other bit which can force the writes to be non-allocating (which indirectly disabled DDIO).

(There is another bit 5 (ForceNoSnoopWrEn) which could force all writes to be non-snooping and thus to be non-allocating. The blog post and the code do not use it. I anyways thought to go give it a try, but setpci is unable to change that bit value — even though the manual says we should have RW permissions on that bit.)

2. Online search suggested that on IceLake, DDIO off option might be provided in BIOS settings. I also unfortunately do not see any option to disable DDIO in our BIOS settings. I also tried disabling VT (Virtualization Technology) setting in the BIOS, but still find DDIO to be used. 

Also attaching the data sheet for IceLake for reference. Please see page number 23 for the register.

[Victor_G_Intel]

Hello SakshamAgarwal,

Thank you so much for contacting Intel customer support,

In this case, the processor model that you have is considered an OEM-only model; therefore, you will have to go directly with the vendor to whom the processor was purchased in order to get any technical information or documentation, once you have reached them out you can ask them to get the information for you by requesting a Field engineer to be assigned to your project or you can also open a ticket in our IPS support channel and request the information there.

Best regards,

Victor G.

Intel Technical Support Technician  

[Victor_G_Intel]

Hello SakshamAgarwal,

Were you able to check the previous post?  

Please let me know if you still need further assistance

Regards,

Victor G.

Intel Technical Support Technician

[SakshamAgarwal]

Hello Victor,

Thanks for the response. 

We did reach out to Dell, and they suggested reaching out to Intel instead for resolving this issue. 

Could you please let me know the steps to open a ticket in the IPS channel? 

Thanks,

Saksham

[Victor_G_Intel]

Hello SakshamAgarwal,

Thank you so much for your response.

In order for you to receive support through our IPS channel you can register by following the steps in the link below:

How to Register and have Access to Intel® Premier Support

https://www.intel.com/content/www/us/en/support/articles/000057045/ethernet-products.html

Once your account has been successfully registered, you can create a ticket by following the video found below:

Intel® Premier Support: Case Creation

https://www.intel.com/content/www/us/en/design/support/ips/training/case-creation.html

Best regards,

Victor G.

Intel Technical Support Technician  

[Victor_G_Intel]

Hello SakshamAgarwal,

Were you able to check the previous post?  

Please let me know if you still need further assistance.

Regards,

Victor G.

Intel Technical Support Technician

[Victor_G_Intel]

Hello SakshamAgarwal,

We have not heard back from you.

If you need any additional information, please submit a new question as this thread will no longer be monitored.

Regards,

Victor G.

Intel Technical Support Technician