Added memory role

2026-08-26 13:14:30 +02:00
parent 3147e4bf78
commit 75725ee688
3 changed files with 98 additions and 0 deletions
@@ -0,0 +1,92 @@
+# Everything that lands on the kernel cmdline goes in one marked block, leaving
+# the existing KERNEL_CMDLINE[default]+= line untouched.
+#
+# systemd.zram=0      - stop zram-generator creating the zram device
+# zswap.*             - module params, must be set before first swap-out
+# ttm.pages_limit     - hard cap on GTT allocation, lifted from the ~50% of RAM
+#                       default. 3959290 pages of 4K = ~15.1 GiB
+# ttm.page_pool_size  - must match pages_limit or allocations can fail
+- name: Add BC-250 kernel parameters
+  become: true
+  ansible.builtin.blockinfile:
+    path: /etc/default/limine
+    marker: '# {mark} ANSIBLE bc250 memory'
+    block: |
+      KERNEL_CMDLINE[default]+=" systemd.zram=0 zswap.enabled=1 zswap.shrinker_enabled=1 zswap.compressor=lz4 zswap.max_pool_percent=20 ttm.pages_limit=3959290 ttm.page_pool_size=3959290"
+  notify: Rebuild initramfs and limine entries
+
+# lz4 must be in the initramfs for zswap to use it from early boot.
+- name: Add lz4 to the initramfs modules
+  become: true
+  ansible.builtin.lineinfile:
+    path: /etc/mkinitcpio.conf
+    regexp: '^MODULES='
+    line: 'MODULES=(lz4)'
+  notify: Rebuild initramfs and limine entries
+
+# CachyOS ships a udev rule that disables zswap when zram comes up.
+# An empty file with the same name overrides it.
+- name: Neutralise the CachyOS zram udev rule
+  become: true
+  ansible.builtin.copy:
+    content: ''
+    dest: /etc/udev/rules.d/30-zram.rules
+    mode: '0644'
+
+- name: Lower swappiness
+  become: true
+  ansible.builtin.copy:
+    content: vm.swappiness=10
+    dest: /etc/sysctl.d/99-bc250.conf
+    mode: '0644'
+  register: sysctl_conf
+
+- name: Apply swappiness now
+  become: true
+  ansible.builtin.command:
+    argv:
+      - sysctl
+      - --system
+  when: sysctl_conf.changed
+  changed_when: true
+
+- name: Create the swap subvolume
+  become: true
+  ansible.builtin.command:
+    argv:
+      - btrfs
+      - subvolume
+      - create
+      - /swap
+  args:
+    creates: /swap
+
+- name: Create the swapfile
+  become: true
+  ansible.builtin.command:
+    argv:
+      - btrfs
+      - filesystem
+      - mkswapfile
+      - --size
+      - 8g
+      - --uuid
+      - clear
+      - /swap/swapfile
+  args:
+    creates: /swap/swapfile
+
+- name: Add the swapfile to fstab
+  become: true
+  ansible.builtin.lineinfile:
+    path: /etc/fstab
+    regexp: '^/swap/swapfile'
+    line: '/swap/swapfile none swap defaults 0 0'
+
+- name: Apply pending initramfs changes
+  ansible.builtin.meta: flush_handlers
+
+- name: Reboot to apply the new kernel parameters
+  become: true
+  ansible.builtin.reboot:
+    reboot_timeout: 600