[Bug 1833322] Re: Consider removing irqbalance from default install on desktop images

[Doug Smythies]

Hi Christian,

Thank you for your reply to my post.

> I do not know the ping pong test,

A simple token passing ring, that is useful for getting the system to utilize shallow idles states. Otherwise it can be difficult to get to such shallow states on my test system, without them being timer based.
While not relevant to this thread, the test presents a challenge for the TEO (Timer Events Orientated) idle governor, and the menu governor should perform better.

> but on iperf, I think that is in the noise
> range as far as I remember.

Agreed. I am just searching for good example type tests is all.

> If you'd just re-run that as-is what is the delta
> on your test box?

Oh. it's repeatable. I just haven't got to re-testing it yet with 24.04
as my host hardware.

> let me ask, what kind of system (cpu, size, nodes, ...)
> was that.

Intel(R) Core(TM) i5-10600K CPU @ 4.10GHz
6 cores, 2 threads per core, 12 CPUs.
HWP enabled (A.K.A. Intel Speed Shift)
intel_pstate CPU frequency driver
powersave governor
teo idle governor (but menu used below)
No throttling involved, ever.

> Your results show no change or minimal
> degradation while at the same time losing
> a bit of power. Have you also had a chance
> to try the powerthresh argument
> that Steve mentioned above?

I was just searching for a good test, and since that post I did find a really good one (not reported here). However, that was with 20.04 which has an old version of irqbalance. So I made my system dual boot adding 24.04. That same test is now not good at all for showing any differences.
And yes, also tested with the powerthresh argument.
Just for completeness, the attached graph shows processor package power and the only other graph that had some slight signal above the noise, the "idle state 1 was to deep" graph.
The test: 6 ping pong pairs, with almost no work done at each stop, 300 million loops. About 27 minutes.
Legend:
irqb-menu-disable: irqbalance disabled, menu governor.
irqb-menu-enable-1: irqbalance enabled with powerthresh=1, menu governor.
irqb-menu-enable: irqbalance enabled, menu governor.

Power: see graph, same for all.
irqbalance disabled: 5.1854 uSec/loop
irqbalance enabled powerthresh=1: 5.1966 uSec/loop
irqbalance enabled: 5.1817 uSec/loop


** Attachment added: "power-and-1-above.png"
   https://bugs.launchpad.net/ubuntu/+source/ubuntu-meta/+bug/1833322/+attachment/5738151/+files/power-and-1-above.png

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https://bugs.launchpad.net/bugs/1833322

Title:
  Consider removing irqbalance from default install on desktop images

Status in Ubuntu on IBM z Systems:
  New
Status in irqbalance package in Ubuntu:
  Confirmed
Status in ubuntu-meta package in Ubuntu:
  Confirmed

Bug description:
  as per https://github.com/pop-os/default-settings/issues/60

  Distribution (run cat /etc/os-release):

  $ cat /etc/os-release
  NAME="Pop!_OS"
  VERSION="19.04"
  ID=ubuntu
  ID_LIKE=debian
  PRETTY_NAME="Pop!_OS 19.04"
  VERSION_ID="19.04"
  HOME_URL="https://system76.com/pop"
  SUPPORT_URL="http://support.system76.com"
  BUG_REPORT_URL="https://github.com/pop-os/pop/issues"
  PRIVACY_POLICY_URL="https://system76.com/privacy"
  VERSION_CODENAME=disco
  UBUNTU_CODENAME=disco

  Related Application and/or Package Version (run apt policy $PACKAGE
  NAME):

  $ apt policy irqbalance
  irqbalance:
  Installed: 1.5.0-3ubuntu1
  Candidate: 1.5.0-3ubuntu1
  Version table:
  *** 1.5.0-3ubuntu1 500
  500 http://us.archive.ubuntu.com/ubuntu disco/main amd64 Packages
  100 /var/lib/dpkg/status

  $ apt rdepends irqbalance
  irqbalance
  Reverse Depends:
  Recommends: ubuntu-standard
  gce-compute-image-packages

  Issue/Bug Description:

  as per konkor/cpufreq#48 and
  http://konkor.github.io/cpufreq/faq/#irqbalance-detected

  irqbalance is technically not needed on desktop systems (supposedly it
  is mainly for servers), and may actually reduce performance and power
  savings. It appears to provide benefits only to server environments
  that have relatively-constant loading. If it is truly a server-
  oriented package, then it shouldn't be installed by default on a
  desktop/laptop system and shouldn't be included in desktop OS images.

  Steps to reproduce (if you know):

  This is potentially an issue with all default installs.

  Expected behavior:

  n/a

  Other Notes:

  I can safely remove it via "sudo apt purge irqbalance" without any
  apparent adverse side-effects. If someone is running a situation where
  they need it, then they always have the option of installing it from
  the repositories.

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