Skip to content

Conversation

@tormath1
Copy link
Contributor

@tormath1 tormath1 commented Sep 11, 2025

With Kernel 6.12 this is disabled by default and this can cause breakage for existing workloads relying on this like the JVM.


Related to: flatcar/Flatcar#1884

diff --git a/tmp/4426.0.0-7E5TbI b/tmp/.-58Genq
index 10139482c2..16c6201253 100644
--- a/tmp/4426.0.0-7E5TbI
+++ b/tmp/.-58Genq
@@ -1,5 +1,5 @@
 File    Size  Used Avail Use% Type
 /boot   127M   64M   63M  51% vfat
-/usr   1016M  455M  331M  58% btrfs
+/usr   1016M  452M  331M  58% btrfs
 /       2.0G  576K  1.8G   1% ext4
-SUM     3.1G  519M  2.2G  19% -
+SUM     3.1G  515M  2.2G  19% -

Before (Max heap size is ~2Gb (half of the host system) while it should be ~1Gb):

core@localhost ~ $ docker run -it -m 2g fedora:41 bash -c "dnf install -y java-headless && java -XX:MaxRAMPercentage=50 -XshowSettings -Xlog:os+container=debug --version"

...
    Max. Heap Size (Estimated): 1.92G
...
core@localhost ~ $ free -m
               total        used        free      shared  buff/cache   available
Mem:            3922         428        2397           0        1329        3493
Swap:              0           0           0

After (Max heap size is now correctly set to ~1Gb):

core@localhost ~ $ docker run -it -m 2g fedora:41 bash -c "dnf install -y java-headless && java -XX:MaxRAMPercentage=50 -XshowSettings -Xlog:os+container=debug --version"
...
    Max. Heap Size (Estimated): 988.00M
...

With Kernel 6.12 this is disabled by default and this can cause breakage
for existing workloads relying on this like the JVM.

Signed-off-by: Mathieu Tortuyaux <[email protected]>
Signed-off-by: Mathieu Tortuyaux <[email protected]>
@github-actions
Copy link

github-actions bot commented Sep 11, 2025

@tormath1 tormath1 marked this pull request as ready for review September 11, 2025 13:47
@tormath1 tormath1 requested a review from a team as a code owner September 11, 2025 13:47
@tormath1 tormath1 merged commit 24fc49b into main Sep 11, 2025
11 checks passed
@github-project-automation github-project-automation bot moved this from ✅ Testing / in Review to Implemented in Flatcar tactical, release planning, and roadmap Sep 11, 2025
@tormath1 tormath1 deleted the tormath1/cpuset branch September 11, 2025 15:22
@tormath1
Copy link
Contributor Author

Cherry-picked to:

  • flatcar-4426
  • flatcar-4372

Sign up for free to join this conversation on GitHub. Already have an account? Sign in to comment

Projects

None yet

Development

Successfully merging this pull request may close these issues.

3 participants