[Bug 2107347] Re: Severe Network Performance Regression with BCM57800/BCM57810 on Kernel 6.8.0-40 through 6.12.16

Ok, I need to confirm this was an env issue:

https://people.canonical.com/~ecanepa/bugs/2107347/linux-6.7.6-060706.519475c5_amd64.tar.gz
https://people.canonical.com/~ecanepa/bugs/2107347/linux-6.7.6-060706.cfc86a96_amd64.tar.gz
https://people.canonical.com/~ecanepa/bugs/2107347/linux-6.7.6-060706.fa658e37_amd64.tar.gz

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Title:
Severe Network Performance Regression with BCM57800/BCM57810 on Kernel
6.8.0-40 through 6.12.16

Status in linux package in Ubuntu:
Confirmed
Status in linux source package in Jammy:
In Progress

Bug description:
Significant network performance degradation when using Broadcom
BCM57800/BCM57810 (bnx2x) NICs with jumbo frames on Ubuntu Jammy with
kernels starting from 6.8.0-38, with the issue becoming severe and
rendering the system unusable from 6.8.0-40 onwards.

There is a similar report here: https://bugs.launchpad.net/ubuntu/+source/linux/+bug/2098961
However, the proposed fix in that report does not resolve the issue for BCM57800 using the bnx2x driver.

Environment:
OS: Ubuntu 22.04(Jammy Jellyfish)
Current HWE Kernel: 6.8.0-57.59~22.04.1
NIC: Broadcom BCM57800 / BCM57810
Driver: bnx2x

Observed Behavior:
Noticeable network degradation begins in kernel 6.8.0-38
Becomes unusable in kernel 6.8.0-40 and beyond
Still reproducible in latest HWE kernel 6.8.0-57
Lowering the MTU to 1500 increases performance

Expected Behavior:
Stable and performant network performance as seen in previous kernel versions

Additional Notes: As mentioned in LP#2098961, the issue appears to be
fixed in kernel 6.12.17[0].

Request that this fix be backported or that further investigation be
made into kernel regressions affecting bnx2x on these NICs.

[0] https://kernel.ubuntu.com/mainline/v6.12.17/

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