Did some more testing and found some interesting results. I forgot to mention the reason for extra SSD is so that I could set up a dual boot with Windows 10 via GRUB. I have discovered it is Windows that is creating my problem.
If I boot straight into Linux from power off I have no latency issues. However if I first boot into Windows, then restart into Linux the latency issue occurs. It is definitely related to ASPM as the Linux kernel pcie_aspm=off flag prevents the issue. I also tested a bunch of settings in the BIOS and the results (NOK means issue still occured): Boot -> Fast Boot -> Disabled - NOK Advanced -> Platform Misc Configuration -> PCI Express Native Power Management -> Disabled - OK Advanced -> Platform Misc Configuration -> Native ASPM -> Disabled - OK Advanced -> PCH Configuration -> ASPM Support -> Disabled - OK Advanced -> PCH Configuration -> ASPM Support -> Auto - NOK Advanced -> PCH Configuration -> ASPM Support -> L0s - OK Advanced -> PCH Configuration -> ASPM Support -> L1 - NOK Advanced -> PCH Configuration -> ASPM Support -> L0sL1 - OK I don't really understand much about ASPM and how OSes and BIOSes control it, but it seems with ASPM support set to auto or L1, then somehow after the system reboots from Windows some sort of state is left set which causes the latency. Possibly related to the L1 state. Anyway I am going to leave ASPM in BIOS set to L0sL1 so that ASPM is still used but whatever Windows is doing is reset by the BIOS. -- You received this bug notification because you are a member of Kernel Packages, which is subscribed to linux in Ubuntu. https://bugs.launchpad.net/bugs/1880076 Title: ubuntu 20.4 - retransmitts with r8169 Status in linux package in Ubuntu: Expired Bug description: Hi, i run some network-tests (iperf3) and noticed massive retransmitts in ubuntu 20.4 with kernel 5.4.0-29. I'm using module r8169 for network- adapter 03:00.0 Ethernet controller: Realtek Semiconductor Co., Ltd. RTL8111/8168/8411 PCI Express Gigabit Ethernet Controller (rev 15) if i boot my ubuntu 18.4 and did same iperf-test (same hardware, same network configuration, other client is not rebooted) i have not these retransmitts. root@bpi-r2:~# iperf3 -c 192.168.0.21 Connecting to host 192.168.0.21, port 5201 [ 5] local 192.168.0.11 port 35702 connected to 192.168.0.21 port 5201 [ ID] Interval Transfer Bitrate Retr Cwnd [ 5] 0.00-1.00 sec 14.2 MBytes 119 Mbits/sec 337 14.1 KBytes [ 5] 1.00-2.00 sec 14.9 MBytes 125 Mbits/sec 331 14.1 KBytes [ 5] 2.00-3.00 sec 15.1 MBytes 126 Mbits/sec 296 19.8 KBytes [ 5] 3.00-4.00 sec 14.7 MBytes 124 Mbits/sec 314 14.1 KBytes [ 5] 4.00-5.00 sec 12.8 MBytes 107 Mbits/sec 259 14.1 KBytes [ 5] 5.00-6.01 sec 67.4 MBytes 560 Mbits/sec 137 362 KBytes [ 5] 6.01-7.00 sec 111 MBytes 940 Mbits/sec 0 366 KBytes [ 5] 7.00-8.00 sec 112 MBytes 941 Mbits/sec 0 409 KBytes [ 5] 8.00-9.00 sec 112 MBytes 940 Mbits/sec 0 421 KBytes [ 5] 9.00-10.00 sec 112 MBytes 936 Mbits/sec 0 426 KBytes - - - - - - - - - - - - - - - - - - - - - - - - - [ ID] Interval Transfer Bitrate Retr [ 5] 0.00-10.00 sec 586 MBytes 491 Mbits/sec 1674 sender [ 5] 0.00-10.01 sec 585 MBytes 491 Mbits/sec receiver iperf Done. 2: enp3s0: <BROADCAST,MULTICAST,UP,LOWER_UP> mtu 1500 qdisc fq_codel state UP group default qlen 1000 link/ether e4:b9:7a:f7:c4:8b brd ff:ff:ff:ff:ff:ff inet 192.168.0.21/24 brd 192.168.0.255 scope global dynamic noprefixroute enp3s0 valid_lft 171856sec preferred_lft 171856sec inet6 fe80::781a:829f:5030:ad6a/64 scope link noprefixroute valid_lft forever preferred_lft forever $ ethtool -S enp3s0 NIC statistics: tx_packets: 571053 rx_packets: 1184934 tx_errors: 0 rx_errors: 0 rx_missed: 1919 <<<<<<<<<<<<<<<<<<<<<<<<<<< align_errors: 0 tx_single_collisions: 0 tx_multi_collisions: 0 unicast: 1184926 broadcast: 6 multicast: 2 tx_aborted: 0 tx_underrun: 0 2: enp3s0: <BROADCAST,MULTICAST,UP,LOWER_UP> mtu 1500 qdisc fq_codel state UP mode DEFAULT group default qlen 1000 link/ether e4:b9:7a:f7:c4:8b brd ff:ff:ff:ff:ff:ff RX: bytes packets errors dropped overrun mcast 1785166133 1184970 0 0 0 2 TX: bytes packets errors dropped carrier collsns 39395440 570500 0 0 0 0 on the other side i see dropped packets, maybe flowcontrol-related? ethtool reports "Link partner advertised pause frame use: Symmetric" but maybe flowcontrol is not working... also driver reports flowcontrol is enabled... $ dmesg | grep r8169 [ 0.939358] libphy: r8169: probed [ 0.939491] r8169 0000:03:00.0 eth0: RTL8168h/8111h, e4:b9:7a:f7:c4:8b, XID 541, IRQ 128 [ 0.939492] r8169 0000:03:00.0 eth0: jumbo features [frames: 9200 bytes, tx checksumming: ko] [ 0.986853] r8169 0000:03:00.0 enp3s0: renamed from eth0 [ 3.478981] Generic FE-GE Realtek PHY r8169-300:00: attached PHY driver [Generic FE-GE Realtek PHY] (mii_bus:phy_addr=r8169-300:00, irq=IGNORE) [ 3.591124] r8169 0000:03:00.0 enp3s0: Link is Down [ 7.171198] r8169 0000:03:00.0 enp3s0: Link is Up - 1Gbps/Full - flow control rx/tx ProblemType: Bug DistroRelease: Ubuntu 20.04 Package: linux-image-5.4.0-29-generic 5.4.0-29.33 ProcVersionSignature: Ubuntu 5.4.0-29.33-generic 5.4.30 Uname: Linux 5.4.0-29-generic x86_64 ApportVersion: 2.20.11-0ubuntu27 Architecture: amd64 AudioDevicesInUse: USER PID ACCESS COMMAND /dev/snd/controlC0: frank 1427 F.... pulseaudio CasperMD5CheckResult: skip CurrentDesktop: GNOME-Flashback:GNOME Date: Fri May 22 06:49:34 2020 InstallationDate: Installed on 2020-04-27 (24 days ago) InstallationMedia: Ubuntu 20.04 LTS "Focal Fossa" - Release amd64 (20200423) MachineType: Dell Inc. G5 5590 ProcEnviron: TERM=xterm-256color PATH=(custom, no user) XDG_RUNTIME_DIR=<set> LANG=de_DE.UTF-8 SHELL=/bin/bash ProcFB: 0 i915drmfb ProcKernelCmdLine: BOOT_IMAGE=/boot/vmlinuz-5.4.0-29-generic root=UUID=7c9113b7-ca65-4c46-9435-f5d2b73bab72 ro quiet RelatedPackageVersions: linux-restricted-modules-5.4.0-29-generic N/A linux-backports-modules-5.4.0-29-generic N/A linux-firmware 1.187 SourcePackage: linux UpgradeStatus: No upgrade log present (probably fresh install) dmi.bios.date: 02/07/2020 dmi.bios.vendor: Dell Inc. dmi.bios.version: 1.12.0 dmi.board.name: 0KW84T dmi.board.vendor: Dell Inc. dmi.board.version: A00 dmi.chassis.type: 10 dmi.chassis.vendor: Dell Inc. dmi.modalias: dmi:bvnDellInc.:bvr1.12.0:bd02/07/2020:svnDellInc.:pnG55590:pvr:rvnDellInc.:rn0KW84T:rvrA00:cvnDellInc.:ct10:cvr: dmi.product.family: GSeries dmi.product.name: G5 5590 dmi.product.sku: 08EA dmi.sys.vendor: Dell Inc. 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