Slow upload speed when using vmxnet3 with macOS Mojave

[mbejaran]

Hey everyone,

I have a late 2018 Mac Mini with the latest version of macOS Mojave 10.14.4 (18E226) hosting two guests with the Mojave as well. I am running the latest version of VMware Fusion 11 Pro. I ordered the Mac Mini with a 10GbaseT ethernet NIC and would like to use the guests at that speed too, if possible.

In macguest1 I changed ethernet0.virtualDev to "e1000e", which is only gigabit speeds, and in macguest2 I changed that to "vmxnet3", which should have full 10 gig speeds. Then I installed speedtest-cli from Homebrew and the results are really terrible:

in macguest1:

macguest1:~ admin$ speedtest

Retrieving speedtest.net configuration...

Testing from Elisa Oyj (x.x.x.x)...

Retrieving speedtest.net server list...

Selecting best server based on ping...

Hosted by Elisa Oyj (Helsinki) [1.31 km]: 2.075 ms

Testing download speed................................................................................

Download: 919.85 Mbit/s

Testing upload speed................................................................................................

Upload: 743.70 Mbit/s

and in macguest2:

macguest2:~ admin$ speedtest

Retrieving speedtest.net configuration...

Testing from Elisa Oyj (x.x.x.x)...

Retrieving speedtest.net server list...

Selecting best server based on ping...

Hosted by Elisa Oyj (Helsinki) [1.31 km]: 2.087 ms

Testing download speed................................................................................

Download: 806.86 Mbit/s

Testing upload speed................................................................................................

Upload: 1.68 Mbit/s

It looks like download speed is fine in both VMs, but the upload speed with macguest2, using a virtual 10gig interface, has a maximum speed of <2Mbit/s! I ran this test multiple times from multiple ISPs and got the same results.

If I switch this to "e1000e" on macguest2, then the upload speed matches macguest1, so it's not an issue with the VM.

Both have the latest version of VMware Tools installed:

macguest1:~ admin$ /Library/Application\ Support/VMware\ Tools/vmware-tools-cli -v

10.3.2.6765 (build-9925305)

macguest2:~ admin$  /Library/Application\ Support/VMware\ Tools/vmware-tools-cli -v

10.3.2.6765 (build-9925305)

This is a really weird issue and I'm not sure what to test next. Has anyone else seen this on their end?

Thanks!

-Miguel

[Sir_Percy]

I think its a limitation of this network adapter - VMXNET3 (VMXNET Generation 3) is a virtual network adapter designed to deliver high performance in virtual machines (VMs) running on the VMware vSphere platform. VMXNET3 has the same features as the VMXNET2 adapter but with added functionality to minimize I/O virtualization overhead.

Maybe due to Fusion being Type II Hypervisor. I might be wrong as well.

[heikkij]

Did you get this resolved ?

I'm seeing the same thing.

[kjdfhaueiase]

I too am curious if you solved this. However, I have discovered something pretty interesting.

The Mac OS VMware tools (darwin.iso) does NOT include the VMXNET3 driver. In fact, it only contains the graphics driver and the uninstaller. It is extremely light (2.7Mb!) compared to the other vmware tools sets.

The only vmxnet3 driver as far as I can tell comes from Apple, and its copyright date is 2017. I have dug through all the darwin.iso files and I have attached the packageinfo.

Who created the driver is unclear to me, and who is responsible for bug fixes is also unclear.

I am getting "decent" speeds but not "excellent" speeds. The kind of speeds I'd impose on VMware users if... you know.. I wanted to sell more hardware instead of letting them concentrate multiple Mac OS instances onto a single apple hardware device.

But even assuming the best intentions, the support of this driver is unclear.

[BROhner]

For me turning off "TCP Segment Offload (TSO)" as described in the following post worked:

https://communities.vmware.com/t5/VMware-Fusion-Discussions/how-do-i-disable-lro-and-tso-on-mac-osx/...

I cannot tell if this has any other negative effects. Hope it helps.

Ben

[aalgrou]

Thanks this works for me too