Re: [Bug 213943] New: Poor network speed with 10G NIC with kernel 5.13 (Intel X710-T2L)

On Thu, 12 Aug 2021 09:25:13 -0700 Stephen Hemminger wrote:

Begin forwarded message:

Date: Mon, 02 Aug 2021 14:05:30 +0000
From: bugzilla-daemon@bugzilla.kernel.org
To: stephen@networkplumber.org
Subject: [Bug 213943] New: Poor network speed with 10G NIC with kernel 5.13 (Intel X710-T2L)


https://bugzilla.kernel.org/show_bug.cgi?id=213943

            Bug ID: 213943
           Summary: Poor network speed with 10G NIC with kernel 5.13
                    (Intel X710-T2L)
           Product: Networking
           Version: 2.5
    Kernel Version: 5.13.x
          Hardware: Intel
                OS: Linux
              Tree: Mainline
            Status: NEW
          Severity: high
          Priority: P1
         Component: IPV4
          Assignee: stephen@networkplumber.org
          Reporter: ealrann@gmail.com
        Regression: No

Hello,

On a server, I use to receive files (parallel cp with NFS4) with a 10g NIC
(Intel X710-T2L). I can usually achieve a total speed close to 1 GB/s
(generally 4 cp at the same time, targeted to 4 different HDD).

Switching to kernel 5.13 (Archlinux) with the exact same configuration, my
speed is now limited at 250MB/s. Rolling back to a previous kernel fix the
speed. 

The problem is maybe in the last Intel driver i40e, but I don't really know how
to investigate more.


The problem still appear in 5.13.7 (last one at the moment).

Jesse, are you aware of anything that could cause this?