CPU core allocation between Efficiency & Performance cores on M1 Max

[Jazmodo]

So I'm running some fairly light tasks on a 16" with M1 Max, with moderate I/O usage, and I'm seeing stutters & skipped frames when playing back some local 4K HDR footage via the Infuse app (to enable MKV playback in HDR without transcoding to MP4 for use in Quicktime). I've got 2TB storage so I/O speed shouldn't be an issue at all.

I've a number of other light apps running, and my 2 Efficiency cores are getting slammed, yet my Performance cores are essentially idling. I've attached some screenshots.

Has anyone else had similar stuttering in local playback of media?
It's only mild, but frequent & noticeable.

Would manually asking OSX to 'prioritise' the app be useful, I've seen a reference to it (https://apple.stackexchange.com/que...crease-decrease-a-priority-of-a-macos-process) but unsure if this would be effective. It seems like a scheduling issue, but not really sure.

 

[LinkRS]

Howdy Jazmodo,

Is the Infuse app running under Rosetta, or it is a universal binary? Are you playing back on the internal display, or are you using an external monitor. Have you tried to play it without the Infuse app to see if you are getting the same behavior? If macOS is trying push the video playback to the Efficiency cores, that would explain the stuttering. From what I understand macOS tries to keep the Performance cores free to respond to user requests and do heavy lifting on-demand. It is one of the reasons that m1 based Macs seem so much more responsive than the older Intel models.

Rich S.

 

[Gnattu]

It is normal those efficiency cores are fully loaded. I'm seeing an Intel app using huge amount of CPU, what is that?

 

[leman]

Is it possible that Infuse is instructing the OS to run the playback tasks on the efficiency cores? Did you post this issue at the Infuse Firecore forum? Devs usually reply very quickly there.

 

[white7561]

So I'm running some fairly light tasks on a 16" with M1 Max, with moderate I/O usage, and I'm seeing stutters & skipped frames when playing back some local 4K HDR footage via the Infuse app (to enable MKV playback in HDR without transcoding to MP4 for use in Quicktime). I've got 2TB storage so I/O speed shouldn't be an issue at all.

I've a number of other light apps running, and my 2 Efficiency cores are getting slammed, yet my Performance cores are essentially idling. I've attached some screenshots.

Has anyone else had similar stuttering in local playback of media?
It's only mild, but frequent & noticeable.

Would manually asking OSX to 'prioritise' the app be useful, I've seen a reference to it (https://apple.stackexchange.com/que...crease-decrease-a-priority-of-a-macos-process) but unsure if this would be effective. It seems like a scheduling issue, but not really sure.

I'm using infuse and it's all fine. Playing 4K HDR MKV on my SMB share. I can tell it's not even using the full efficiency cores playing em.

What kind of videos are you playing? In terms of codec etc. Since i can tell that it's HW decoding in H264 and HEVC even in 4K HDR . The only thing rendered using the CPU/software decoding is VP9 from YouTube. Seems like to hw decode it u need chrome or other browsers . AKA on local players it doesn't seem to hw decode

 

[Jazmodo]

Howdy Jazmodo,

Is the Infuse app running under Rosetta, or it is a universal binary? Are you playing back on the internal display, or are you using an external monitor. Have you tried to play it without the Infuse app to see if you are getting the same behavior? If macOS is trying push the video playback to the Efficiency cores, that would explain the stuttering. From what I understand macOS tries to keep the Performance cores free to respond to user requests and do heavy lifting on-demand. It is one of the reasons that m1 based Macs seem so much more responsive than the older Intel models.

Rich S.

Hey Rich, Infuse is universal binary, I think playback stutters are probably a secondary issue caused by the core utilisation, as White below suggests all the decoding is done HW accelerated, so shouldn't really be affected by CPU utilisation (even though it is!)

I'm using infuse and it's all fine. Playing 4K HDR MKV on my SMB share. I can tell it's not even using the full efficiency cores playing em.

What kind of videos are you playing? In terms of codec etc. Since i can tell that it's HW decoding in H264 and HEVC even in 4K HDR . The only thing rendered using the CPU/software decoding is VP9 from YouTube. Seems like to hw decode it u need chrome or other browsers . AKA on local players it doesn't seem to hw decode

Great to hear Cheers White. I closed down the apps running in Rosetta and the stutters cleared up. The files (Matrix & The Expanse) are all in HEVC.

It is normal those efficiency cores are fully loaded. I'm seeing an Intel app using huge amount of CPU, what is that?

Private Internet Access (a VPN) and a chrome extension - they're the 2 main 'intel' process hogs

Is it possible that Infuse is instructing the OS to run the playback tasks on the efficiency cores? Did you post this issue at the Infuse Firecore forum? Devs usually reply very quickly there.

Possibly, that or the scheduler isn't swapping the threads to the Performance cores when the Efficiency cores get bogged down.
I didn't even think of posting on their forums though, I'll head over there now

 

[white7561]

Hey Rich, Infuse is universal binary, I think playback stutters are probably a secondary issue caused by the core utilisation, as White below suggests all the decoding is done HW accelerated, so shouldn't really be affected by CPU utilisation (even though it is!)

Great to hear Cheers White. I closed down the apps running in Rosetta and the stutters cleared up. The files (Matrix & The Expanse) are all in HEVC.


Private Internet Access (a VPN) and a chrome extension - they're the 2 main 'intel' process hogs


Possibly, that or the scheduler isn't swapping the threads to the Performance cores when the Efficiency cores get bogged down.
I didn't even think of posting on their forums though, I'll head over there now

Oh then it's prob fine

 

[Krevnik]

Possibly, that or the scheduler isn't swapping the threads to the Performance cores when the Efficiency cores get bogged down.

Because of how the XNU scheduler works, these should never touch the efficiency cores in the first place. Only tasks that are utility or background QoS can be scheduled on the efficiency cores, which video playback isn't.

EDIT: Work for the performance cores can wind up on the efficiency cores, but only after all the performance cores have been fully utilized. And when that happens, they get top priority for the efficiency cores, above all the background work they normally handle.

 

[Jazmodo]

Followed Leman's advice above and headed over to the Firecore forums, looks to be a known issue they're working on:

https://community.firecore.com/t/choppy-playback-in-macos-monterey-on-m1-max/34899/23

Beta testing a fix currently it seems