Slow / low CPU utilization on Alder Lake, due to lower-priority non-GUI threads being limited to E Cores

[DeeDeeG]

Hi,

Thank you for making FFMetrics!

Issue:

I noticed the program spawns an ffmpeg process under the hood with lower than "Normal" priority.

On Alder Lake, since the ffmpeg process is non-GUI, and is less than "Normal" priority, it will always run only on E cores. (For me with four E cores, that shows FFMetrics as having ~20% CPU utilization in Task Manager.) I can manually increase the priority of ffpmpeg to "Normal" in Task Manager, and it will use both P and E cores, and increase FFMetrics to having about ~60% total CPU utilization in Task Manager, and run significantly faster.

But this requires manual intervention for every ffmpeg process that is spawned, which would be very tedious and not practical.

Since intel and Microsoft together have made these "interesting" scheduling decisions, may I politely/humbly request some workaround for those of us on Alder Lake CPUs?

Additional Notes:

(Possibly affects all intel CPUs with E cores? I only have Alder Lake to test with. And I'm on Windows 10, unsure about Windows 11)...

(If I recall correctly, any non-GUI process can't be a "foregrounded window." If its priority is both less than "Normal" and a "background task," the scheduler will strictly limit it to E cores. This is from my best recollection, pardon me if I misstate the details. This saves wattage but is painfully slow.)

("Below Normal" and "Low" priority for the ffmpeg process in Task Manager are about equivalent -- they behave very similarly. Maybe a ~1% utilization increase from "Low" to "Below Normal"? Both around ~20% utilization. "Normal" is significantly faster and significantly higher utilization than either "Low" or "Below Normal.")

Thanks again for making FFMetrics!

[fifonik]

Ah.
Just recently I've changed the priority to iddle: #193
Looks like the only choice to make everyone happy is to add an option somewhere (in GUI or in conf).

[DeeDeeG]

Yeah, I saw that issue :/ Sorry to make the opposite request as that person.

An option somewhere does indeed seem like it would address the issue for any need around the priority level. 👍

(It's not at all urgent to me, I just wanted to post the issue before I forgot again. I had noticed this last year initially, but I forgot to post an issue at the time).

[fifonik]

Uploaded a new beta where FFMpeg calls priority can be adjusted for different operations using FFMetrics.conf (I did not add it in UI as I do not think it need to be changed often).
The default for metrics' calculation is still 'Low/Idle', but you can change it to anything from the list: 'Low', 'BelowNormal', 'Normal', 'AboveNormal', 'High', 'Realtime' by creating FFMetrics.conf with the following content:

{
  "Metric": {
    "Priority": "..."
  }
}

Priority for other FFMpeg calls is changed from "BelowNormal" to "Normal" and can also be adjusted (see FFMetrics.conf.example)

[DeeDeeG]

Thank you!

It's working well for me when setting

  "Metric": {
    "Priority": "Normal"
  }

in FFMetrics.conf.

CPU usage can go up to about ~93% or so for PSNR and ~95% for SSIM! I think VMAF and XPSNR are less-well-threaded since they use less than 90%, but it's a lot faster and more CPU usage than Low or BelowNormal!

(I also tried AboveNormal since I was curious, both Normal and AboveNormal worked about the same.)

Thanks again!