Vsync issue when use IDD (Indirect display driver) in Windows 11

[-AlbertWang-]

Hi,

My laptop is equipped with an i5-1340P processor, no dedicated GPU, running on Windows 11 64-bit with Intel graphics driver version 32.0.101.5768.

In this environment, I developed a program using Unity and enabled Vsync within the Unity settings. When the IDD (Indirect Display Driver) is not activated, the program runs at 60 FPS on my laptop's screen. However, once IDD is enabled, the program’s FPS aligns with the 120Hz refresh rate of the external monitor connected via HDMI and changes according to the external display's refresh rate.

It’s worth noting that I haven’t encountered this issue when using AMD or Nvidia GPUs.

Could you please help me resolve this issue? Thank you!

[JeanetteC_Intel]

Hello -AlbertWang-,

Thank you for posting in Intel Communities.

I would like to know more about your application (Unity) and system details to fully understand where the issue truly lies. Please confirm if the application (Unity) same as this app (Unity Real-Time Development Platform | 3D, 2D, VR & AR Engine) or a different one.

Additionally, we highly appreciate you sharing your system configuration so we can fully check and provide you with an accurate fix. This could be possible by downloading the Intel® System Support Utility for Windows* software. When the download is complete, launch SSU.exe.

1. Scan: Check the box Everything.
2. Click Scan.
3. Review: When finished scanning, click Next.
4. Click Save (.txt)

I will wait for your reply.

Best regards,

Jeanette C.

Intel® Customer Support Technician

[-AlbertWang-]

Hi JeanetteC,

Yes, the Unity is the same as this app (Unity Real-Time Development Platform | 3D, 2D, VR & AR Engine)

Here is the ssu.txt and the template file for bug report.

Thanks for your help.

[Felipe_Intel]

Hello Albert! please create a new thread in the gaming developing forum for this issue. Please include the link to this post for reference so you don't have to write the description all over again.

Here is the link to the forum https://community.intel.com/t5/Developing-Games-on-Intel/bd-p/developing-games-graphics

Let us know here when you create the new post so we can close this one.

We will create a new case for it and continue communications there.

[karen_intel]

Heey @-AlbertWang-  TY for reaching out Intel Game Developer Support, I will be assisting you in this case

Allow me to do some debug/research on this case and I will get back with my results

Also, could you explain a bit better what's the expected behavior of IDD? Is it to match the refresh rate of the onboard display?

Stay tuned!

Karen

[-AlbertWang-]

Hi Karen,

IDD will create a virtual display in Windows.

The supported timings of the virtual display can be configured in the IDD driver.

In my IDD setup, only 1920x1080 @ 60Hz is supported.

I have an external HDMI monitor with a refresh rate of 120Hz, while the laptop screen has a refresh rate of 60Hz.

With VSync enabled in my Unity app, the FPS will match the refresh rate of the display on which the app is running.

But when IDD is active and create the virtual display.

The FPS will be locked to the 120Hz refresh rate of the external display, even when the app is running on the laptop's screen.

I expected that an active IDD would not lock the VSync FPS, and this issue does not occur on Nvidia or AMD graphics cards.

Thanks for your help.

[karen_intel]

Ty @-AlbertWang- for the details!

Allow me to create an internal report for this and I'll get back to you with the number.

Stay tuned!

Karen

[-AlbertWang-]

Hi Karen,

May I kindly ask if any update on this issue?

Thanks for your time
Albert

[karen_intel]

Hi Albert!

We're still working on it! As part of our debug process we need to test with a couple builds before submitting our internal report. 
By next week I think I'll have it TY for your patience!

Karen

[-AlbertWang-]

Hi Karen,

Hope all is going well! Just wanted to check in on the internal report. Last time, you mentioned it might be ready by last week. I was wondering if there’s been any progress or a new estimated completion time?

Thanks so much for all your hard work!

Albert

[karen_intel]

Hey @-AlbertWang- yeah sorry for the delay!

We want to test this issue in one of our newest machines, which wasn't available last week unfortunately.

But I will share my findings tomorrow Talk to you soon!

Karen

[karen_intel]

Ok @-AlbertWang- update on this!

I've been testing the .exe on a MTL machine with the latest driver and yeah I see a very erratic behavior on FPS

I still need to verify in other GPUs to detect the exact symptom so, stay tuned! Actively working on this, specially as it doesn't look good

Karen

[-AlbertWang-]

Hi Karen, 

Thank you for the update!

I've shared a short video that might help identify the issue:
https://youtu.be/3dHRgth1N60.

I used the Intel Graphics Performance Analyzer to open the Unity app. In the app, a window that mirrors the desktop takes 720 frames to move from one end to the other.

Initially, the IDD is inactive, and the FPS is 120, matching the refresh rate of the external monitor. This results in the window taking about 6 seconds to move from left to right.

However, once the IDD becomes active, the FPS drops to 60, matching the refresh rate of my laptop screen, causing the window to take around 12 seconds to complete the same movement.

Thanks again for your help!

Albert

[karen_intel]

Hey @-AlbertWang- TY for the information!

FYI I just got the instruction to contact directly the developer of IDD. We need more details on expected performance on Intel Products so I'm reaching out to them and their feedback is necessary for my report! 

Stay tuned!

Karen

[-AlbertWang-]

Hi Karen,

Sorry to bother you, but it’s been a while since we last connected, so I wanted to check in to see if there are any updates on this matter.

Have you received any new information from the IDD developer?

Thanks so much, and I really appreciate your help!

[karen_intel]

Hey @-AlbertWang- no feedback from the developer so far

We asked a couple of questions in their GitHub repo but looks like their support is limited ATM.

We definitely need the cooperation from the developers of this and any other software that's reported to us as we need to understand why this behavior is happening in Intel products and cooperate to fix it.

Some devs decide not to support a specific HW brands and that's something we also must know.

It is also a requirement from the development team to understand the impact of the issue and start working on it but without any feedback from them is very difficult to pursue it and have a successful collaboration.

If I hear from them, I will let you know

Karen

[-AlbertWang-]

Hi Karen,

We have found that the issue is resolved when upgrading to Windows 11 version 24H2.

Since IDD is an API provided by Windows, could you please inquire with Microsoft regarding how to resolve this issue on operating systems that are not running Windows 11 version 24H2?

Thank you.

[karen_intel]

Heey @-AlbertWang- thanks for confirming the fix of the issue!

The best would be to open the case directly with Microsoft, so I'd recommend posting in their forums.

On Intel's end, I will create a public article about your findings in case anyone else has seen the same behavior and know what to do

Karen