[Bug 1862044] Re: packet loss, extra latency and lower bandwidth on bionic

[Pauloone]

This second graph shows during the same run the number of packets per
second this time.

YOu can see that Xenial is sending less packets per second than bionic.

Also this is the output of tc -s qdisc for the second bionic node:

qdisc fq_codel 0: dev enp3s0 root refcnt 2 limit 10240p flows 1024 quantum 1514 target 5.0ms interval 100.0ms memory_limit 32Mb ecn 
 Sent 254067572631 bytes 675644785 pkt (dropped 1732, overlimits 0 requeues 627) 
 backlog 0b 0p requeues 627

As you can see packet drop is reported, an only that test as been run
this this machine as been created.

this is the same output for the Xenial node:

qdisc pfifo_fast 0: dev enp3s0 root refcnt 2 bands 3 priomap  1 2 2 2 1 2 0 0 1 1 1 1 1 1 1 1
 Sent 326734300816 bytes 555522299 pkt (dropped 0, overlimits 0 requeues 558309) 

as you can see no packet drop, but we this machine exist since way
longer time.



** Attachment added: "packets trhoughput"
   https://bugs.launchpad.net/ubuntu/+source/systemd/+bug/1862044/+attachment/5325973/+files/packets%20throughput.png

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https://bugs.launchpad.net/bugs/1862044

Title:
  packet loss, extra latency and lower bandwidth on bionic

Status in systemd package in Ubuntu:
  Incomplete

Bug description:
  We are investigating migrating our servers from Xenial to Bionic.
  We are seeing significant network differences between the 2 LTS versions.
  Using the same hardware an machines connected to a single swith on the same network, we see:
  10% less packets throuput on bionic in comparision to Xenial when running uperf.
  Also "tc -s qdisc" report packets been dropped on Bionic but not Xenial.
  The command iperf -c <host> -u -d -p 20 timeout on Bionic and not on Xenial, and if you reduce the value of p, you will see more packet drops on Bionic.

  We tryied to upgrade the xenial kernel to the same version than
  bionic. We did not see any improvement.

  All the tests are performed with 4 identical physical machines
  connected to the same physical switch. With one bionic machine, one
  Xenial machine and 2 extra Xenial machine that act as iperf/uperf
  clients.

  All 4 nodes are configured as ntp peers with each others. Under load,
  the bionic machine see siginificant jitter improvement with the 3
  others machines. We don't see that with the Xenial hosts.

  I doesn't seems to be an hardware compatibility issue as we see
  significant network performance loss in our datacenter on fully
  different hardware.

  ProblemType: Bug
  DistroRelease: Ubuntu 18.04
  Package: iperf 2.0.10+dfsg1-1ubuntu0.18.04.2
  ProcVersionSignature: Ubuntu 4.15.0-76.86-lowlatency 4.15.18
  Uname: Linux 4.15.0-76-lowlatency x86_64
  ApportVersion: 2.20.9-0ubuntu7.9
  Architecture: amd64
  Date: Wed Feb 5 17:14:25 2020
  Dependencies:
   gcc-8-base 8.3.0-6ubuntu1~18.04.1
   libc6 2.27-3ubuntu1
   libgcc1 1:8.3.0-6ubuntu1~18.04.1
   libstdc++6 8.3.0-6ubuntu1~18.04.1
  InstallationDate: Installed on 2020-01-29 (7 days ago)
  InstallationMedia: Ubuntu-Server 18.04.3 LTS "Bionic Beaver" - Release amd64 (20190805)
  ProcEnviron:
   TERM=xterm-256color
   PATH=(custom, no user)
   XDG_RUNTIME_DIR=<set>
   LANG=en_US.UTF-8
   SHELL=/bin/bash
  SourcePackage: iperf
  UpgradeStatus: No upgrade log present (probably fresh install)

  ProblemType: Bug
  DistroRelease: Ubuntu 18.04
  Package: systemd 237-3ubuntu10.29
  ProcVersionSignature: Ubuntu 4.15.0-76.86-lowlatency 4.15.18
  Uname: Linux 4.15.0-76-lowlatency x86_64
  ApportVersion: 2.20.9-0ubuntu7.9
  Architecture: amd64
  Date: Wed Feb  5 17:29:53 2020
  ExecutablePath: /lib/systemd/systemd
  InstallationDate: Installed on 2020-01-29 (7 days ago)
  InstallationMedia: Ubuntu-Server 18.04.3 LTS "Bionic Beaver" - Release amd64 (20190805)
  MachineType: Dell Inc. XPS 8700
  ProcEnviron:
   TERM=linux
   PATH=(custom, no user)
  ProcKernelCmdLine: BOOT_IMAGE=/vmlinuz-4.15.0-76-lowlatency root=UUID=400563c9-8749-47b7-8abb-1efdb57bc589 ro
  SourcePackage: systemd
  UpgradeStatus: No upgrade log present (probably fresh install)
  dmi.bios.date: 05/16/2013
  dmi.bios.vendor: Dell Inc.
  dmi.bios.version: A01
  dmi.board.name: 0KWVT8
  dmi.board.vendor: Dell Inc.
  dmi.board.version: A00
  dmi.chassis.type: 3
  dmi.chassis.vendor: Dell Inc.
  dmi.modalias: dmi:bvnDellInc.:bvrA01:bd05/16/2013:svnDellInc.:pnXPS8700:pvr:rvnDellInc.:rn0KWVT8:rvrA00:cvnDellInc.:ct3:cvr:
  dmi.product.family: To be filled by O.E.M.
  dmi.product.name: XPS 8700
  dmi.sys.vendor: Dell Inc.

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