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Memory allocation

The memory_limit attributes high and max control how much memory is allocated to the QM partition.

  • high controls the throttling limit for memory use in the QM partition. The value of high can be set in bytes or as a percentage value.

  • max controls the absolute limit for memory use in the QM partition. The max attribute can also be in bytes or a percentage value.

You can configure these values in the qm stage of your Automotive Image Builder manifest file.

qm:
  memory_limit:
    max: 50%
    high: 45%

Out of Memory killer

The Linux kernel memory management system includes the Out of Memory (OOM) killer. The OOM killer terminates processes to release memory when memory becomes critically low. This mechanism ensures that critical processes in the root partition have enough memory to continue to run.

The oom_score_adj parameter influences the likelihood that a process will be terminated by the OOM killer. When an operating system experiences memory constraints, the OOM killer uses the processes’ oom_score_adj values to prioritize which processes to terminate.

The value of oom_score_adj can range from 1000 to -1000. The OOM killer terminates processes with the highest oom_score_adj values first. If a process is set to -1000, the OOM killer cannot terminate it, whereas the OOM killer would terminate a process set to 1000 first.

When Podman starts a container nested in the QM partition, it writes the default value of 750 into /proc/$PID/oom_score_adj. For more information about oom_score_adj, refer to man 5 proc_pid_oom_score_adj.

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