Win 11 scheduler issues?

meimeiriver · Dec 17, 2021

I do a lot of video processing, using x265. Recently upgraded to Windows 11, and decided to do a render job again. To my dismay, I noticed the CPU saturation is not optimal. Core 0 and 1 are at 100% (as they should be); the rest, however, lingers around 80%. This is no good. And I've always had full CPU saturation on Windows 10.

I don't have an Alderlake (with known scheduler issues), just a regular i7 11700K. Anyone else seen this? I didn't buy an octa core, only to lose 20% in Windows 11, afterwards.

And is there any way to 'repair' it?

Thanks.

glasskuter · Dec 18, 2021

Are you overclocking? If so, turn off overclocking to test load balance to see if it makes any difference. Check with your manufacturer to make sure all drivers are up to date. Go to Intel Intel® Chipset Software and Drivers Check for any updated chipset drivers there.

Download an app called HWMonitor (Free classic version) Hardware Monitor. It's layout is easy to read and it can tell you if any of your cores run hotter than others. Temperature may be an issue.

Close your apps and run a stress test on your cpu. Personally, I use Aida64 in conjunction with HWMonitor, but you can also use the free Intel Extreme Tuning Utility to stress your hardware.

Hope this gives you a place to start.

iko22 · Dec 18, 2021

meimeiriver said:
Core 0 and 1 are at 100% (as they should be); the rest, however, lingers around 80%. This is no good. And I've always had full CPU saturation on Windows 10.

Video rendering is now handled by DirectX 12 API in Windows 11. Could be you are seeing less saturation on CPU loads, because workloads are now handled by the GPU. See: Microsoft DirectX H264/265 Video Encode API now available for Intel and NVIDIA GPUs, AMD in Q2 2022 - VideoCardz.com . Improvements to this API are not due until 2022. Maybe that answers your question. Next question is, what is happening on GPU, when you render H.265?

meimeiriver · Dec 18, 2021

I should have been more clear. Normally (that is: on Windows 10) I get near full 100% cpu saturation on all cores. And no, not overclocking, or an overheat issue. Mind you, a job like this can take easily take a day or so.

My GPU is usually at ca. 25% load during the render. That is because I let DGDecNV handle the decoding, and 'KNLmeansCL' do the denoising (also using the GPU). x265 (and x24 before) tend to really grab 100% CPU (as well they should). Windows 11 simply doesn't want to saturate all cores. Drops ca. 10C degrees off my job (now low 70ties), but a job like this normally runs a little over 80C, at a full 100%).

PerpetualCycle · Dec 18, 2021

iko22 said:
Video rendering is now handled by DirectX 12 API in Windows 11. Could be you are seeing less saturation on CPU loads, because workloads are now handled by the GPU. See: Microsoft DirectX H264/265 Video Encode API now available for Intel and NVIDIA GPUs, AMD in Q2 2022 - VideoCardz.com . Improvements to this API are not due until 2022. Maybe that answers your question. Next question is, what is happening on GPU, when you render H.265?

Article says requires an nvidia card 20xx or higher. In addition, believe applications have to be programmed to use it and this was just published this month. Don't think it is relevant.

glaskutter had a good suggestion. HWInfo64 will show whether your processor is throttling and for what reason. It will at least let you rule out throttling. You don't need to run a stress test, just your rendering.

meimeiriver · Dec 18, 2021

geneo said:
Article says requires an nvidia card 20xx or higher. In addition, believe applications have to be programmed to use it and this was just published this month. Don't think it is relevant.

glaskutter had a good suggestion. HWInfo64 will show whether your processor is throttling and for what reason. It will at least let you rule out throttling. You don't need to run a stress test, just your rendering.

As you can tell, CPU is severely undersaturated; and my temps are alll good (see image). Keep in mind that I've been doing this a LOT, prior to the Windows 11 upgrade. Typically (because I enforce power limit, not overheating), I get an all-core sppeed of ca. 3.9 Ghz. It's way below that now (primarily because the cores don't get pushed to their limit, it seems).

PerpetualCycle · Dec 18, 2021

There is a section in HWInfo64 where throttling information sensors are reported with values of Y/N, with Y indicating it is throttling. What does that look like?

meimeiriver · Dec 18, 2021

geneo said:
There is a section in HWInfo64 where throttling information sensors are reported with values of Y/N, with Y indicating it is throttling. What does that look like?

As expected, it only reports throttling due to Power Limit Exceeded (as it should: I am cooling on air, and I don't want the CPU to run at 90C all the time).

As I mentioned, though, my setup hasn't changed. I simply upgraded to Win 11, and where I got a near 100% all-core saturation before, now all is significantly lower.

PerpetualCycle · Dec 18, 2021

So if you raise the power limit in BIOS, does it perform better.

I don't know about the 11th gen or your board, but with my 10th Asus board, you can set the effective TJMax temperature. This is the temperature where the processor thermal throttles and is usually around 100c. if the processor reaches that temperature it will throttle down the multiplier. If you set this to a lesser temperature, it will throttle at that temperature instead of 100. I set mine to 80 or 85; it works well. I find it works more reliably than power throttling, so I set my power limits high and the effective TJMax as mentioned.

Anyhow just a thought, though it may be some other issue.

iko22 · Dec 19, 2021

geneo said:
Article says requires an nvidia card 20xx or higher. In addition, believe applications have to be programmed to use it and this was just published this month. Don't think it is relevant.

Partially correct. Article states Nvidia RTX 20xx and above, AND GTX 10xx and above. O.P. has GTX 1080 Ti, so is supported with driver version v471.41.
Applications do actually need to use the new API. So probably wont affect existing programs until they are updated as I originally implied - thanks. O.P. states they are using DGDecNV and KNLmeansCL, which are both shareware/freeware. Could be that these are updated. Not all features are available until 2022 anyway. It was just an idea that might explain the users scenario.

Throttling is also possible, except the user states the observed performance was obtained in Windows 10, on same hardware.

iko22 · Dec 19, 2021

meimeiriver said:
As I mentioned, though, my setup hasn't changed. I simply upgraded to Win 11, and where I got a near 100% all-core saturation before, now all is significantly lower.

Are you noticing the render taking longer on Windows 11 compared to Windows 10? That is the real crucial measure. After all, CPU saturation only means the CPU cannot cope. You just want the render to be as quick as possible. There used to be an era when large USB writes would saturate the CPU. Now on modern systems the writes barely take up 20-30% CPU utilisation, and it is just as quick. What you are seeing could be a system's improvement, that is all I am suggesting.

meimeiriver · Dec 19, 2021

iko22 said:
Partially correct. Article states Nvidia RTX 20xx and above, AND GTX 10xx and above. O.P. has GTX 1080 Ti, so is supported with driver version v471.41.
Applications do actually need to use the new API. So probably wont affect existing programs until they are updated as I originally implied - thanks. O.P. states they are using DGDecNV and KNLmeansCL, which are both shareware/freeware. Could be that these are updated. Not all features are available until 2022 anyway. It was just an idea that might explain the users scenario.

Throttling is also possible, except the user states the observed performance was obtained in Windows 10, on same hardware.

Yeah. Both DGDecNV and KNLmeansCL use nVidia's CUDA API (kinda old already, but still provides a significant computational boost). Hadn't heard about the DX12 API yet, tbh; but I think it may take a while before we'll see it in non-commercial software.

meimeiriver · Dec 19, 2021

iko22 said:
Are you noticing the render taking longer on Windows 11 compared to Windows 10? That is the real crucial measure. After all, CPU saturation only means the CPU cannot cope. You just want the render to be as quick as possible. There used to be an era when large USB writes would saturate the CPU. Now on modern systems the writes barely take up 20-30% CPU utilisation, and it is just as quick. What you are seeing could be a system's improvement, that is all I am suggesting.

Ask me again in a day or so, when the render is done. :) (Yes, denoising 4K material still takes a while, even on an 11th gen CPU).

The most simple and reliable method of testing, for me, has always been fps. Heretofore, on Win 10, I averaged at ca. 8 fps (for the denoising process). It has fallen back to ca. 5 fps in Windows 11.