[SRU] Improve debian/99-gce.rules to set schedulers based on disk

[Chloé Smith]

[SRU]
=======

[Overview]

We should reduce the scope of the `udev` rules in d/99-gce.rules, and change the 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.

[ 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.
 * This can also be done independently with a PPA hooked into CPC's bootstrap
   scripts (kajiya's PPA here: [0])

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

[ Regression potential / Where problems could occur ]

* This may affect users who are already modifying the file (d/99-gce.rules) via
  a startup script on boot [2]; there have been no edits since 2017 so it's a
  pretty well established file.

* There could also be issues if a non-rotating disk is interpreted as a rotating
  disk (and vice-versa). This shouldn't be a big problem in practice though, as
  the named scheduler is "none" which works well on both types anyway.

[Additional Information]

This bug is used to track the release of this new version for all the supported suites, as per the policy mentioned here [1].

[0]: https://launchpad.net/~kajiya/+archive/ubuntu/gce-compute-image-packages
[1]: https://wiki.ubuntu.com/google-compute-engine-oslogin-Updates
[2]: https://cloud.google.com/compute/docs/instances/startup-scripts/linux

[Utkarsh Gupta (utkarsh)]

MP reviewed @ https://code.launchpad.net/~kajiya/ubuntu/+source/gce-compute-image-packages/+git/gce-compute-image-packages/+merge/455766/comments/1223948.

[Launchpad Janitor (janitor)]

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 <email address hidden> Mon, 16 Oct 2023 22:59:06 +0100

[Chloé Smith (kajiya)]

I'll add debdiffs of the different suites shortly...

[Łukasz Zemczak (sil2100)]

Hello Chloé, or anyone else affected,

Accepted gce-compute-image-packages into jammy-proposed. The package will build now and be available at https://launchpad.net/ubuntu/+source/gce-compute-image-packages/20230808.00-0ubuntu1~22.04.1 in a few hours, and then in the -proposed repository.

Please help us by testing this new package. See https://wiki.ubuntu.com/Testing/EnableProposed for documentation on how to enable and use -proposed. Your feedback will aid us getting this update out to other Ubuntu users.

If this package fixes the bug for you, please add a comment to this bug, mentioning the version of the package you tested, what testing has been performed on the package and change the tag from verification-needed-jammy to verification-done-jammy. If it does not fix the bug for you, please add a comment stating that, and change the tag to verification-failed-jammy. In either case, without details of your testing we will not be able to proceed.

Further information regarding the verification process can be found at https://wiki.ubuntu.com/QATeam/PerformingSRUVerification . Thank you in advance for helping!

N.B. The updated package will be released to -updates after the bug(s) fixed by this package have been verified and the package has been in -proposed for a minimum of 7 days.

[Łukasz Zemczak (sil2100)]

Hello Chloé, or anyone else affected,

Accepted gce-compute-image-packages into focal-proposed. The package will build now and be available at https://launchpad.net/ubuntu/+source/gce-compute-image-packages/20230808.00-0ubuntu1~20.04.1 in a few hours, and then in the -proposed repository.

Please help us by testing this new package. See https://wiki.ubuntu.com/Testing/EnableProposed for documentation on how to enable and use -proposed. Your feedback will aid us getting this update out to other Ubuntu users.

If this package fixes the bug for you, please add a comment to this bug, mentioning the version of the package you tested, what testing has been performed on the package and change the tag from verification-needed-focal to verification-done-focal. If it does not fix the bug for you, please add a comment stating that, and change the tag to verification-failed-focal. In either case, without details of your testing we will not be able to proceed.

Further information regarding the verification process can be found at https://wiki.ubuntu.com/QATeam/PerformingSRUVerification . Thank you in advance for helping!

N.B. The updated package will be released to -updates after the bug(s) fixed by this package have been verified and the package has been in -proposed for a minimum of 7 days.

[Łukasz Zemczak (sil2100)]

I have accepted the packages into jammy-proposed and focal-proposed, but I have one request before we proceed with releasing it at some point. The SRU is missing the regression potential analysis. What are the possible regression vectors for this udev rule change? What could go wrong? Please describe that as part of the verification for the package.

Thank you.

[Robie Basak (racb)]

Accepting into Mantic - the change is the same as the one in jammy-proposed, and I see no reason to differ in Mantic.

[Robie Basak (racb)]

Hello Chloé, or anyone else affected,

Accepted gce-compute-image-packages into mantic-proposed. The package will build now and be available at https://launchpad.net/ubuntu/+source/gce-compute-image-packages/20230808.00-0ubuntu2~23.10.0 in a few hours, and then in the -proposed repository.

Please help us by testing this new package. See https://wiki.ubuntu.com/Testing/EnableProposed for documentation on how to enable and use -proposed. Your feedback will aid us getting this update out to other Ubuntu users.

If this package fixes the bug for you, please add a comment to this bug, mentioning the version of the package you tested, what testing has been performed on the package and change the tag from verification-needed-mantic to verification-done-mantic. If it does not fix the bug for you, please add a comment stating that, and change the tag to verification-failed-mantic. In either case, without details of your testing we will not be able to proceed.

Further information regarding the verification process can be found at https://wiki.ubuntu.com/QATeam/PerformingSRUVerification . Thank you in advance for helping!

N.B. The updated package will be released to -updates after the bug(s) fixed by this package have been verified and the package has been in -proposed for a minimum of 7 days.

[Andrew Cloke (andrew-cloke)]

As outlined in the [Test Case] for mantic and jammy:

 * Images have been built with these packages from the -proposed pocket and
   published in the `ubuntu-os-cloud-image-proposed` project
 * The images have gone through CPC's own CTF framework and testing has been successful
 * The images have been shared with the Google team and their testing has also been successful

The Google's team testing of the focal images is still ongoing.

[Andrew Cloke (andrew-cloke)]

As outlined in the [Test Case] for focal:

 * Images have been built with these packages from the -proposed pocket and
   published in the `ubuntu-os-cloud-image-proposed` project
 * The images have gone through CPC's own CTF framework and testing has been successful
 * The images have been shared with the Google team and their testing has also been successful

[Launchpad Janitor (janitor)]

This bug was fixed in the package gce-compute-image-packages - 20230808.00-0ubuntu2~23.10.0

---------------
gce-compute-image-packages (20230808.00-0ubuntu2~23.10.0) mantic; 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 <email address hidden> Tue, 09 Jan 2024 22:50:47 +0000

[Andreas Hasenack (ahasenack)]

The verification of the Stable Release Update for gce-compute-image-packages has completed successfully and the package is now being released to -updates. Subsequently, the Ubuntu Stable Release Updates Team is being unsubscribed and will not receive messages about this bug report. In the event that you encounter a regression using the package from -updates please report a new bug using ubuntu-bug and tag the bug report regression-update so we can easily find any regressions.

[Launchpad Janitor (janitor)]

This bug was fixed in the package gce-compute-image-packages - 20230808.00-0ubuntu1~22.04.1

---------------
gce-compute-image-packages (20230808.00-0ubuntu1~22.04.1) jammy; 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 <email address hidden> Tue, 09 Jan 2024 23:19:03 +0000

[Launchpad Janitor (janitor)]

This bug was fixed in the package gce-compute-image-packages - 20230808.00-0ubuntu1~20.04.1

---------------
gce-compute-image-packages (20230808.00-0ubuntu1~20.04.1) focal; 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 <email address hidden> Tue, 09 Jan 2024 23:46:16 +0000