Max Ethernet Download Speed Varies GREATLY on M1 Max Processor Load

[Kevin Barre]

I noticed that my maximum ethernet download speed drops to a crawl when I've got the M1 Max rendering video with Handbrake. Anyone else seeing this problem?

I can run Speedtest.net and get 370+ Mbps. As soon as I engage Handbrake rendering, it drops to a max of 13 Mbps, but will jump right back up to 370+ if I pause the video encoding.

It's not disk dependent, as the rendering source and destination disk is not the same drive—or even on the same bus—as my download scratch disk. Wondering if this has something to do with basically everything being on the same processor.
I even replaced all of the cables in the network with Cat-6. It did nothing. Even transfers within my home network are adversely affected.

My gut feeling is that this is an M1 issue. This machine exists as a movie server in my house, sending video via Plex to multiple AppleTVs. I was not having these problems before with the 10-year old Mac Mini that had the exact same configuration. Even that ancient machine could render video at full-tilt and still manage to serve 4K movies within the home network at the same time. I had to pause rendering on the M1 last night to even be able to load Plex on a networked AppleTV. The Mac Studio wouldn't even attempt to serve out a 9GB HD video while rendering occurred. Again, I never had these issues with a Late 2012 Mac Mini, with a 2.6 Ghz i7.

Machine: Mac Studio (2022), M1Max, 32 GB RAM, OS 12.3.1

 

[Sheepish-Lord]

Just want to make sure I read this correctly; a 10yr old Mac Mini could do EXACTLY what your Mac Studio is doing and not have any issues?

You realize this is hard to believe right?

 

[Nermal]

I don't find it hard to believe. The Ethernet controller should be independent from the CPU/GPU. The post is giving me flashbacks to the Power Mac 5200, which had all sorts of craziness when you tried to do too many things at once.

I'd be interesting in hearing whether other people can replicate the same issue (I'm on Intel so can't try myself).

 

[satcomer]

I said this before Monterey use something called Ethernet Energy Saver (Apple even Use Gigit Ethernet Port on Mac so to get max speed on Ethernet that use only the manual IP Advanced button in Network System Preference ! This should speed up if you use CAT6a cables!

 

[AltecX]

Just want to make sure I read this correctly; a 10yr old Mac Mini could do EXACTLY what your Mac Studio is doing and not have any issues?

You realize this is hard to believe right?

You're taking that statement totally out of context, You realize that right?

 

[BanditoB]

Is Handbrake the only application to cause this issue? Can you replicate this situation with any other software that loads the processor up?

 

[donawalt]

I am not a Hand Brake expert, but I have it, and I have an M1 Max with 64GB Ethernet connected too. I have a Comcast 1.2 GB D/L service. I took a 8 GB 13:42 MOV video and converted to 1080p 30 surround MKV file, it took about 3 minutes. I constantly ran Speediest during the conversion, and every time it was in the 900-920Mbps download speed range, which is totally normal. So there isn't anything universal going on, there may be something interfering on your Mac or it's setting specific. I am happy to try something else if I am able to.

 

[satcomer]

Plus I know from the past Handbreak is designed to use 100% of processor! it could affected you being to anything else!

 

[jav6454]

I doubt the CPU has any sway over the negotiated speed, the Ethernet controller does.

 

[StudioMacs]

I noticed that my maximum ethernet download speed drops to a crawl when I've got the M1 Max rendering video with Handbrake. Anyone else seeing this problem?

I can run Speedtest.net and get 370+ Mbps. As soon as I engage Handbrake rendering, it drops to a max of 13 Mbps, but will jump right back up to 370+ if I pause the video encoding.

It's not disk dependent, as the rendering source and destination disk is not the same drive—or even on the same bus—as my download scratch disk. Wondering if this has something to do with basically everything being on the same processor.
I even replaced all of the cables in the network with Cat-6. It did nothing. Even transfers within my home network are adversely affected.

My gut feeling is that this is an M1 issue. This machine exists as a movie server in my house, sending video via Plex to multiple AppleTVs. I was not having these problems before with the 10-year old Mac Mini that had the exact same configuration. Even that ancient machine could render video at full-tilt and still manage to serve 4K movies within the home network at the same time. I had to pause rendering on the M1 last night to even be able to load Plex on a networked AppleTV. The Mac Studio wouldn't even attempt to serve out a 9GB HD video while rendering occurred. Again, I never had these issues with a Late 2012 Mac Mini, with a 2.6 Ghz i7.

Machine: Mac Studio (2022), M1Max, 32 GB RAM, OS 12.3.1

This is an older support page, but see if these steps help (especially the part about Energy Efficient Ethernet): https://support.studionetworksoluti...ions-for-video-editors-using-Mac-workstations

 

[mr_roboto]

I noticed that my maximum ethernet download speed drops to a crawl when I've got the M1 Max rendering video with Handbrake. Anyone else seeing this problem?

I can run Speedtest.net and get 370+ Mbps. As soon as I engage Handbrake rendering, it drops to a max of 13 Mbps, but will jump right back up to 370+ if I pause the video encoding.

It's not disk dependent, as the rendering source and destination disk is not the same drive—or even on the same bus—as my download scratch disk. Wondering if this has something to do with basically everything being on the same processor.
I even replaced all of the cables in the network with Cat-6. It did nothing. Even transfers within my home network are adversely affected.

My gut feeling is that this is an M1 issue. This machine exists as a movie server in my house, sending video via Plex to multiple AppleTVs. I was not having these problems before with the 10-year old Mac Mini that had the exact same configuration. Even that ancient machine could render video at full-tilt and still manage to serve 4K movies within the home network at the same time. I had to pause rendering on the M1 last night to even be able to load Plex on a networked AppleTV. The Mac Studio wouldn't even attempt to serve out a 9GB HD video while rendering occurred. Again, I never had these issues with a Late 2012 Mac Mini, with a 2.6 Ghz i7.

Machine: Mac Studio (2022), M1Max, 32 GB RAM, OS 12.3.1

One possibility that comes to mind is that this could be a macOS scheduler issue where Handbrake rendering is taking all the performance cores, other stuff like your download gets pushed to efficiency cores, and performance suffers. If there's a way to tell Handbrake the maximum number of threads to use, try setting it to 6 and see if that improves things.

 

[fakestrawberryflavor]

Packets still get processed by CPU cores. Ethernet chipsets and associated drivers also have an impact. M1 architecture scheduler differences during load/idle. Lots of variables here.

My first thought is what Ethernet hipster are you using and wonder if M1 Monterey has good drivers for it or not. Then I wonder if the Monterey scheduler is prioritizing handbrake tasks above Ethernet frames, which is very likely. I would assume the efficiency cores would be available for stuff like Ethernet while the performance cores are doing real work, but could be wrong.

 

[mi7chy]

First thing to suspect is if the network interface is doing hardware offloading for things like checksum calculation instead of passing the burden to the CPU which, if already bogged down by handbrake, can slow down network throughput as checksum calculation is slowed. You don't see this issue on the Intel Mac Mini since it does hardware offloading, however, if you disable IP/TCP/UDP hardware checksum offloading then run ipperf3 you'll see throughput dropping by about half