Fwd: e1000e - slow receive / rx - i219-LM (Alder Lake)

[Bagas Sanjaya <bagasdotme@gmail.com>]

Hi,

I noticed a regression report on bugzilla [1]. As many developers don't
take a look on it, I decided to forward it by email. To reach the
reporter, though, you need to log in to bugzilla.

Quoting from the report:
>  Scott Silverman 2023-03-03 17:55:10 UTC > When running kernels 5.15 and newer, poor rx speeds are observed on Alder Lake i219-LM (8086:1A1C) on a Dell Precision 3260 Compact.
> 
> To Reproduce:
> Using iperf3 from the system under test:
> `iperf3 -c <server on local LAN> -R`
> 
> Under kernels 5.7-5.14 (inclusive) performance is near line rate, ~990 Mbps.
> From kernels 5.15 through 6.2 performance is approximately 10-20 Mbps.
> 
> Also of note, the issue doesn't present with servers over the internet (i.e. higher latency links). Over a link with a latency of approximately 20ms I was able to achieve about 600Mbps.
> 
> Interesting workaround, on affected kernels (5.15+) I am able to resolve the issue if an additional device is installed into the systems PCIe slot (tested with an Intel i210 NIC (not connected to LAN) and an Nvidia Quadro P620 GPU).

See bugzilla for details.

To the reporter: It had been great if you also test the latest mainline
(6.4-rc1) to see if this regression has been already fixed.

Anyway, I'm adding this to regzbot:

#regzbot introduced: v5.14..v5.15 https://bugzilla.kernel.org/show_bug.cgi?id=217120
#regzbot title: e1000e performance drop (slow receive/rx) on i219-LM (Alder Lake)

Thanks.

[1]: https://bugzilla.kernel.org/show_bug.cgi?id=217120

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