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Getting 25 Gbps Thunderbolt Ethernet on My Mac Studio

jeffgeerling.com

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Re: Getting 25 Gbps Thunderbolt Ethernet on My Mac Studio

#4

Post by areoform »

pzmarzly wrote: post #2

One of the YouTube comments pointed out the issue is most likely the lack of support for SMB Direct (RDMA) in macOS. Would be nice to repeat the test on a Windows/Linux laptop.

https://developer.apple.com/documentation/technotes/tn3205-l...

MacOS has supported RDMA over thunderbolt since March 19th.

Re: Getting 25 Gbps Thunderbolt Ethernet on My Mac Studio

#5

Post by wmf »

teaearlgraycold wrote: post #3

It’s crazy that the Ethernet chips consume more power (presumably - because of the heat) than the processor in the computer. How is driving 25Gb/s such a hot task compared to driving multiple 40Gb/s Thunderbolt ports?

A Mac Studio is over 100 W while a 25G NIC is under 25 W (that's the power limit for a normal PCIe slot).

Re: Getting 25 Gbps Thunderbolt Ethernet on My Mac Studio

#6

Post by throwaway219450 »

teaearlgraycold wrote: post #3

It’s crazy that the Ethernet chips consume more power (presumably - because of the heat) than the processor in the computer. How is driving 25Gb/s such a hot task compared to driving multiple 40Gb/s Thunderbolt ports?

They’re not that bad, but even a couple watts of power with no way to dissipate is going to get hot enough to burn you. Forced air cooling over a heatsink is really effective. 15W under load is much lower than a high end desktop CPU that can pull 150-200W.

See also NVMe drives? They draw enough idle power to drain a laptop battery overnight, and will easily hit 60+C in a bad enclosure. That’s only a 10Gbps module. The USB4 enclosures are all heatsink.

Re: Getting 25 Gbps Thunderbolt Ethernet on My Mac Studio

#7

Post by AnthonBerg »

teaearlgraycold wrote: post #3

It’s crazy that the Ethernet chips consume more power (presumably - because of the heat) than the processor in the computer. How is driving 25Gb/s such a hot task compared to driving multiple 40Gb/s Thunderbolt ports?

As I understand it, it takes a bit of anger to get electromagnetism to wiggle that fast over copper. Imperfect transistors using their full operational envelope to control a sort of chaotic thing? Fields and stuff.

Re: Getting 25 Gbps Thunderbolt Ethernet on My Mac Studio

#8

Post by wrs »

areoform wrote: post #4
pzmarzly wrote: post #2

One of the YouTube comments pointed out the issue is most likely the lack of support for SMB Direct (RDMA) in macOS. Would be nice to repeat the test on a Windows/Linux laptop.

https://developer.apple.com/documentation/technotes/tn3205-l... MacOS has supported RDMA over thunderbolt since March 19th.

That is just RDMA itself and seems to be aimed directly at distributed inference (no surprise there!). Now they need to update the SMB driver to make use of it.

Re: Getting 25 Gbps Thunderbolt Ethernet on My Mac Studio

#9

Post by nutjob2 »

Somewhat off-topic: has anyone implemented USB C based networking?

So for instance you have two or more machines that have USB 4 ports at 20 to 80 Gbps and you plug in the appropriate USB C cables to connect them.

What do you need to make the connections appear as a (point to point) part of a regular TCP/IP network? Seems much cheaper than Ethernet if you already have the ports.

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