Only scrub when plugged in on Linux, and TCP optimization.

ansible/roles/base/tasks/linux.yaml

@@ -26,17 +26,6 @@
     daemon_reload: yes
     enabled: yes
 
-# Of questionable value since I don't use swap on my machines
-- name: Configure sysctls for swap
-  sysctl:
-    name: "{{ item.name }}"
-    value: "{{ item.value }}"
-    state: present
-    sysctl_file: /etc/sysctl.d/swap.conf
-  loop:
-    - name: vm.swappiness
-      value: 10
-
 - name: Install scripts
   copy:
     src: "files/{{ item.src }}"
@@ -49,3 +38,31 @@
       dest: /usr/local/bin/mount_disk_image
     - src: watch_linux
       dest: /usr/local/bin/ww
+
+- name: Configure sysctls
+  sysctl:
+    name: "{{ item.name }}"
+    value: "{{ item.value }}"
+    state: present
+    sysctl_file: /etc/sysctl.d/{{ item.file }}
+  loop:
+    # Of questionable value since I don't use swap on my machines
+    - name: vm.swappiness
+      value: 10
+      file: swap.conf
+    # Enable TCP packetization-layer PMTUD when an ICMP black hole is detected.
+    - name: net.ipv4.tcp_mtu_probing
+      value: 1
+      file: tcp.conf
+    # Switch to bbr tcp congestion control which should be better on lossy connections like bad wifi.
+    - name: net.ipv4.tcp_congestion_control
+      value: bbr
+      file: tcp.conf
+    # Don't do a slow start after a connection has been idle for a single RTO.
+    - name: net.ipv4.tcp_slow_start_after_idle
+      value: 0
+      file: tcp.conf
+    # 3x time to accumulate filesystem changes before flushing to disk.
+    - name: vm.dirty_writeback_centisecs
+      value: 1500
+      file: power.conf

ansible/roles/zfs/files/linux_scrub_when_plugged_in.conf

@@ -0,0 +1,2 @@
+[Unit]
+ConditionACPower=true

ansible/roles/zfs/tasks/linux.yaml

@@ -61,3 +61,26 @@
     name: "zfs-scrub-weekly@{{ item }}.timer"
     daemon_reload: yes
   loop: "{{ periodic_scrub_pools }}"
+
+- name: Create directories
+  when: periodic_scrub_pools is defined
+  file:
+    name: "{{ item }}"
+    state: directory
+    mode: 0755
+    owner: root
+    group: wheel # Normally it is "root"
+  loop:
+    - /etc/systemd/system/zfs-scrub-weekly@.timer.d
+
+- name: Install Configuration
+  when: periodic_scrub_pools is defined
+  copy:
+    src: "files/{{ item.src }}"
+    dest: "{{ item.dest }}"
+    mode: 0644
+    owner: root
+    group: wheel # Normally it is "root"
+  loop:
+    - src: linux_scrub_when_plugged_in.conf
+      dest: /etc/systemd/system/zfs-scrub-weekly@.timer.d/override.conf