Slow Networking Performance Only In 1 Direction

[greengolftee87]

I've been chasing this problem for a few weeks now so I have a decent amount of info but can't figure out this issue at all. I have narrowed the issue down to 1 PC though.

Tools used: iperf3 -P 20

All computers are using Intel 82599 10g SFP+ NICS with DAC cables to a 10g SFP+ switch.

The computer having the issue is running Windows 10 with the latest intel drivers. It also is using Hyper-V so there are vEthernet adapters involved (not sure if this is relevant but whatever).

Win10 box to Issue PC:

[SUM] 0.00-10.00 sec 1.96 GBytes 1.69 Gbits/sec sender
[SUM] 0.00-10.00 sec 1.96 GBytes 1.69 Gbits/sec receiver

Issue PC to Win10 box:

[SUM] 0.00-10.00 sec 8.42 GBytes 7.23 Gbits/sec sender
[SUM] 0.00-10.00 sec 8.42 GBytes 7.23 Gbits/sec receiver

Linux to Issue PC:

[SUM] 0.00-10.00 sec 1.91 GBytes 1.64 Gbits/sec sender
[SUM] 0.00-10.00 sec 1.90 GBytes 1.63 Gbits/sec receiver

Issue PC to Linux:

[SUM] 0.00-10.00 sec 9.17 GBytes 7.88 Gbits/sec sender
[SUM] 0.00-10.00 sec 9.17 GBytes 7.88 Gbits/sec receiver

I loaded up Linux Live onto the issue PC and was able to get 9.2Gbits/sec in both directions so its for sure a windows configuration/setting issue but I cant find anything wrong. Jumbo frames are off on all PCs. This issues manifests itself in real life when moving files so it's not just a theoretical problem. 

I've been through the intel guideline for tuning and it suggests that RSS should be disabled and VMQ be enabled but VMQ is NOT an option in the latest drivers.  It also does seem that CPU 0 spikes during the slow transfer leading me to think this is close to the issue - but again, despite the intel website saying it supports it, I can't find any kind of setting for VMQ. Anyway  I've played with the RSS setting with no change.

[greengolftee87]

If anyone is curious the way to solve this problem is to get rid of the Intel NIC and put in a Broadcom one and everything just works.

[Sachinks]

Hello greengolftee87,

Thank you for posting in the Intel Community. We sincerely apologize for the delay in our response. We have received your concern and would like to assure you that assisting you is our top priority.

Could you kindly let us know if the issue has been resolved, or if you require further assistance from us? Your prompt response will greatly help us in diagnosing and resolving the issue as quickly as possible.

We appreciate your patience and understanding, and we look forward to hearing from you soon.

Regards,

Sachin KS

Intel Customer Support Technician

[greengolftee87]

I solved the problem but not in a good way.  There is an issue with the way Hyper-V is handling the connection.  The way that I solved it was to have only the host OS use the new 10g adapter and attached the VM in Hyper-V to a different vSwitch to a different network adapter. If the host OS and the VM use the same vSwitch and network adapter that is where the problem is.

Download speeds are still half of upload so the issue isn't completely resolved but for now that is faster than my drives can write so it's not effecting me.

[Sachinks]

Hello greengolftee87,

Thank you for your reply and thank you for sharing your resolution!

From your reply, we understand that using a different vSwitch connected to a different network adapter in the hypervisor resolved the issue.

Kindly let us know if we can go ahead and archive this thread for now.

Please don’t hesitate to contact us for any further assistance.

Thank you for using Intel products and services.

Regards,

Sachin KS

Intel Customer Support Technician