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How to disable Data Direct I/O (DDIO) on Intel Xeon E5?

Junsheng_T_Intel
Employee
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I'm wondering whether it's possible to disable Intel Data Direct I/O on Xeon E5 processor. It'e mentioned that "Intel DDIO is enabled by default on all Intel Xeon processor E5 family and Intel Xeon processor E7 v2 family platforms." in http://www.intel.com/content/www/us/en/io/data-direct-i-o-technology.html http://www.intel.com/content/www/us/en/io/data-direct-i-o-technology.html but I couldn't find any documents saying how to disable DDIO.

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11 Replies
idata
Employee
5,959 Views

Hello Jensontan,

I would like to verify some things related to your inquiry.

1. Is there a reasoning behind why you want to disable the feature?

 

2. Some of the technologies are not capable of being disabled, please keep that in mind since it could be "built-in" the processor

 

3. If there is a chance of disabling it, that would be done by the BIOS of the board

 

4. Could I have the model of the board you are currently using for the system?

With this information, I will be able to further investigate this matter, and therefore, assist you.

Regards,

 

Esteban C
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Junsheng_T_Intel
Employee
5,959 Views

Hello Esteban

Thank you for your reply!

1, We are currently investigating how NUMA( non-uniform memory access) and NUIOA (non-uniform I/O access) can affect applications' performence in a general way. However, We think Intel DDIO technology is targeted on Intel E5 processor family an E7 v2 processors only, we want to disable it such that our experiment setup is more general.and the experiment results could be more general, too;

2, Our server is Inspur NF8420M3. The processors are Intel Xeon E5-4603. The Server Manual mentions that I can disable the Intel I/O Acceleration Technology (Intel I/OAT) by the BIOS, but I don't think Intel I/OAT is same as Intel DDIO according to http://www.intel.com/content/www/us/en/wireless-network/accel-technology.html http://www.intel.com/content/www/us/en/wireless-network/accel-technology.html.

Best Regards,

Jenson Tan

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idata
Employee
5,959 Views

Hello Jensontan,

Thank you for the clarification!

I would like to further investigate this matter, as soon as I get an outcome, I will let you know

Regards,

 

Esteban C
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Junsheng_T_Intel
Employee
5,959 Views

Hello Esteban C,

Thank you so much!

Best Regards,

Jenson Tan

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idata
Employee
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Junsheng_T_Intel
Employee
5,959 Views

Hi,

Thank you for your information. But I don't think DDIO is a part of VT-d. Intel VT-d is used in virtualization and it enables device access isolating between different virtual machines. AMD calls this technology as "I/O MMU". However, Intel DDIO can work in both virtualization environment and native host environment.

Regards,

Jenson

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idata
Employee
5,959 Views

Hello Jensontan,

 

 

Let me elaborate more about VT-d and DDIO.

 

 

I will be providing an answerto you at the soonest.

 

 

Regards,

 

Esteban C

 

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idata
Employee
5,959 Views

Hello Jensontan,

 

We don't disagree with your comment about DDIO being independent of virtualization. However, it looks like from what I can tell it has been bundled VT from a product implementation perspective and that is how it is enabled and disabled in the BIOS by some vendors. Have you checked your BIOS, it varies from vendor to vendor? Your question is a practical enablement question, not the theory of what it does or its design goals. There are numerous presentations that address that.

Some additional information to backup the answer.

Intel® Xeon® E5-2600 v3 Product Family (formerly codename # Haswell) has added four new technologies to the already strong Intel® Virtualization Technology (Intel VT) portfolio. Doesn't matter whether you use containers and virtual machines (VMs), or you focus on servers, storage or networking, or you work in the cloud or enterprise or some hybrid environment – with the new Intel® VT technologies, you are in for a treat.

The additions are:

 

1.# Cache Monitoring Technology (CMT)

 

2.# Virtual Machine Control Structure (VMCS) Shadowing

 

3.# Logging of the Accessed and Dirty bits in Extended Page Tables (EPT A/D bits), and

 

4.# Data Direct IO (DDIO) enhancements

Source

https://software.intel.com/en-us/blogs/2014/09/08/four-new-virtualization-technologies-on-the-latest-intel-xeon-are-you-ready-to https://software.intel.com/en-us/blogs/2014/09/08/four-new-virtualization-technologies-on-the-latest-intel-xeon-are-you-ready-to

 

Regards,

 

Esteban C
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Junsheng_T_Intel
Employee
5,959 Views

Hi Esteban,

Thank you for your information. The DDIO could be part of Intel Virtualization Technology (Intel VT), but you should note that Intel VT is quite different from Intel VT-d. I think Intel VT is a bit like generic terms, which includes CMT, VMCS, DDIO etc. But Intel VT-d is a specific virtualization technology. In fact,some virtualization hypervisor like KVM replies on VT-d. If you disable VT-d, the KVM cannot work. So I do think DDIO is not VT-d, it might be part of Intel VT.

In my BIOS, there is a switch to disable/enable VT-d, but no DDIO or Intel VT switches.

Regards,

Jenson

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idata
Employee
5,959 Views

Your response seems consistent with the article that Jenson posted above, that it is a part of VT, not VT-d.

It also doesn't look like it is recommended by Intel Dev Zone to disable it.

https://software.intel.com/en-us/articles/financial-services-industry-fsi-frequently-asked-questions Financial Services Industry (FSI) - Frequently Asked Questions | Intel® Software

That aside it also doesn't look like all vendors even offer it as an option in their BIOS, sounds like it isn't an option in your BIOS. To be sure you would have to contact the BIOS manufacturer to verify or see if they have a different version with the option.

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Junsheng_T_Intel
Employee
5,959 Views

Hi mseszeny, thank you for your information!

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