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= Increase vm.max_map_count value <!-- The name of your change proposal --> =
= Increase vm.max_map_count value <!-- The name of your change proposal --> =


{{Change_Proposal_Banner}}


== Summary ==
== Summary ==
<!-- A sentence or two summarizing what this change is and what it will do. This information is used for the overall changeset summary page for each release. Note that motivation for the change should be in the Benefit to Fedora section below, and this part should answer the question "What?" rather than "Why?". -->
<!-- A sentence or two summarizing what this change is and what it will do. This information is used for the overall changeset summary page for each release. Note that motivation for the change should be in the Benefit to Fedora section below, and this part should answer the question "What?" rather than "Why?". -->
This change aims at increasing the default value of the vm.max_map_count sysctl
This change aims at increasing the default value of the `vm.max_map_count` sysctl


== Owner ==
== Owner ==
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== Current status ==
== Current status ==
[[Category:ChangeReadyForWrangler]]
[[Category:ChangeAcceptedF39]]
<!-- When your change proposal page is completed and ready for review and announcement -->
<!-- When your change proposal page is completed and ready for review and announcement -->
<!-- remove Category:ChangePageIncomplete and change it to Category:ChangeReadyForWrangler -->
<!-- remove Category:ChangePageIncomplete and change it to Category:ChangeReadyForWrangler -->
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ON_QA -> change is fully code complete
ON_QA -> change is fully code complete
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* FESCo issue: <will be assigned by the Wrangler>
* [https://lists.fedoraproject.org/archives/list/devel@lists.fedoraproject.org/thread/WVWHTLXSGZN4QMAE577ZFZX4ZI6YZF3A/ devel thread]
* Tracker bug: <will be assigned by the Wrangler>
* FESCo issue: [https://pagure.io/fesco/issue/2993 #2993]
* Release notes tracker: <will be assigned by the Wrangler>
* Tracker bug: [https://bugzilla.redhat.com/show_bug.cgi?id=2216765 #2216765]
* Release notes tracker: [https://pagure.io/fedora-docs/release-notes/issue/997 #997]


== Detailed Description ==
== Detailed Description ==
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The goal is to improve compatibility with Windows games through wine or steam. Read on "Benefit to Fedora" for examples.
The goal is to improve compatibility with Windows games through wine or steam. Read on "Benefit to Fedora" for examples.


Steam Deck is shipping with a default of `2147483642` (MAX_INT - 5) up from `65530` of Fedora; it makes sense to follow their lead and set the same value.
It was agreed to set the limit to `1048576`, up from the Linux default `65530`.


== Feedback ==
== Feedback ==
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== How To Test ==
== How To Test ==
Temporarily set the new value with `​sudo sysctl -w vm.max_map_count=2147483642`
Temporarily set the new value with `​sudo sysctl -w vm.max_map_count=1048576`


Run any of the software listed above to verify that it now works.
Run any of the software listed above to verify that it now works.

Latest revision as of 14:03, 22 June 2023

Increase vm.max_map_count value

Summary

This change aims at increasing the default value of the vm.max_map_count sysctl

Owner


Current status

Detailed Description

Increase the vm.max_map_count sysctl default value.

The goal is to improve compatibility with Windows games through wine or steam. Read on "Benefit to Fedora" for examples.

It was agreed to set the limit to 1048576, up from the Linux default 65530.

Feedback

This was briefly discussed in #fedora-devel and received positively. Concerns over possible downsides were raised. I am not aware of any, but more input here is desired.

Benefit to Fedora

The following Windows games will work out of the box (through wine or steam):

Scope

  • Proposal owners: Add the new default to /usr/lib/sysctl.d/
  • Other developers: No work will be necessary unless the new default is found breaking some software
  • Release engineering: N/A (not needed for this Change)
  • Policies and guidelines: N/A (not needed for this Change)
  • Trademark approval: N/A (not needed for this Change)
  • Alignment with Community Initiatives: N/A

Upgrade/compatibility impact

Upgrading to the new Fedora release will seamlessly update the default. No manual intervention is necessary.

How To Test

Temporarily set the new value with ​sudo sysctl -w vm.max_map_count=1048576

Run any of the software listed above to verify that it now works.

Or run any other software to verify the change causes no regression.


User Experience

More Windows games will work out-of-the-box (through wine or steam)

Dependencies

None


Contingency Plan

  • Contingency mechanism: Revert the shipped configuration
  • Contingency deadline: Final Freeze
  • Blocks release? No


Documentation

The default value is currently hard-coded in the kernel, at https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/tree/include/linux/mm.h?h=v6.2.12#n203 . It cannot be changed through the kernel defconfig, instead it must be set through sysctl.

Release Notes

The default value of the vm.max_map_count sysctl is increased