[Bug 2045708] Re: Improve debian/99-gce.rules to set schedulers based on disk

[Launchpad Bug Tracker]

This bug was fixed in the package gce-compute-image-packages -
20230808.00-0ubuntu2

---------------
gce-compute-image-packages (20230808.00-0ubuntu2) noble; urgency=medium

  * debian/99-gce.rules:
    * The previous rule forced an I/O scheduler on all disk types. This
      has now been re-scoped to only affect HDDs.
    * The I/O scheduler has also been changed from "NOOP" to "NONE"
      which performed much better in testing.
    * LP: #2045708.

 -- Chloé 'kajiya' Smith <chloe.smith at canonical.com>  Mon, 16 Oct 2023
22:59:06 +0100

** Changed in: gce-compute-image-packages (Ubuntu)
       Status: New => Fix Released

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https://bugs.launchpad.net/bugs/2045708

Title:
  Improve debian/99-gce.rules to set schedulers based on disk

Status in gce-compute-image-packages package in Ubuntu:
  Fix Released

Bug description:
  We should reduce the `udev` rule scope here and change I/O scheduler.
  The previous `udev` rule was drastically reducing the bootspeed on SSD
  backed instances, as the `noop` scheduler is pretty old school.

  I did pretty extensive experimentation and found that swapping to
  "none" in this file yielded the best results on HDD instances (>10s
  improvement in boot time on average). Letting SSD's just roll
  independently also seemed to give the best speeds.

  [ Test Plan ]

   * I built test GCP images with this file changed as proposed [0]
     * This can be done with a PPA hooked into CPC bootstrap scripts (kajiya's here: [1])

  [ Where problems could occur ]

   * I can't see any regressions happening as we're moving _from_ `noop` _to_ not using a scheduler at all
     (`none`), which was the original behaviour before this file was introduced.

  SRU
  ====

  [ Impact ]

   * If an end user launches an Ubuntu instance in GCE backed with a HDD, no
     scheduler will be used natively.

   * This package is provided upstream by Google themselves, and is part of a
     collection of tools and that ensures that the Ubuntu images published to GCE
     run properly on the platform.

  [Test Case]

  When this package lands in -proposed, the following will happen:

   * an image built with this package from -proposed will be built for GCE and
     published in the `ubuntu-os-cloud-image-proposed` project
   * The image will go through CPC's own CTF framework, and assuming it passes
     will be handed to the Google team to perform their own verification.

  If all the testing indicates that the image containing the new package
  is good, verification is considered finished.

  [0]: https://code.launchpad.net/~kajiya/ubuntu/+source/gce-compute-image-packages/+git/gce-compute-image-packages/+merge/455766
  [1]: https://launchpad.net/~kajiya/+archive/ubuntu/gce-compute-image-packages

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