userspace-resource-manager-extensions

8. Post-Boot Init Scripts

Directory: initscripts/post_boot/

Purpose

Post-boot scripts apply target-specific kernel and sysfs tuning at system startup, for example to configure CPU governor, RT scheduling, memory management, etc.

Script Inventory

Script Purpose
post_boot.sh Dispatcher: runs common + target-specific scripts
post_boot_common.sh Common kernel tuning applied to all targets
post_boot_alorp.sh ALORP kernel tuning
post_boot_qcm6490.sh QCM6490 kernel tuning
post_boot_qcs615.sh QCS615 kernel tuning
post_boot_qcs8300.sh QCS8300 kernel tuning
post_boot_qcs9075.sh QCS9075 kernel tuning
post_boot_qcs9100.sh QCS9100 kernel tuning

All scripts are installed to /usr/libexec/urm/initscripts/post_boot/ with execute permissions (755).

Dispatcher Script (post_boot.sh)

The dispatcher script:

  1. Reads /proc/meminfo to compute RAM_MB and exports it for use by child scripts.
  2. Runs post_boot_common.sh (if it exists and is executable).
  3. Reads /sys/devices/soc0/machine to detect the target name.
  4. Lowercases the machine name using tr.
  5. Applies machine name aliases:
    • sa8775p → qcs9100
    • sa7255p → qcs8300
    • qcs6490 → qcm6490
  6. Runs post_boot_${machine}.sh if it exists and is executable.

Target detection is fully automatic - no manual configuration needed.

Common Script (post_boot_common.sh)

Applied to all targets before the target-specific script. Settings:

Setting Value Rationale
CPU governor schedutil Energy-aware; tracks actual CPU load
mem_sleep s2idle Fast resume for embedded/always-on use
vm.swappiness 100 Aggressive swap to free RAM for workloads
THP enabled never (if RAM < 15 GB) Disable transparent huge pages on low-RAM targets
ZRAM mem_limit RAM_MB / 2 Cap ZRAM usage to half of physical RAM

Target-Specific Script Contents

All target-specific scripts (alorp, qcm6490, qcs615, qcs8300, qcs9075, qcs9100) apply the following settings:

Setting Value Rationale
sched_util_clamp_min_rt_default 0 Disable minimum utilization clamp for RT tasks
vm.compaction_proactiveness 0 Disable proactive THP compaction (THP not used)

Scripts for qcm6490, qcs615, qcs8300, qcs9075, and qcs9100 additionally apply:

Setting Value Rationale
system.slice cpuset.cpus 0-3 Restrict system slice to little cores
kernel.printk 4 Suppress debug/info kernel messages

The alorp script does not restrict system.slice or printk level.

Adding a New Target Script

  1. Create initscripts/post_boot/post_boot_NEWTARGET.sh
  2. The dispatcher will automatically pick it up based on /sys/devices/soc0/machine
  3. If the hardware reports a different machine name, add an alias case to post_boot.sh
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