Feature 57 (config and provisioning): modules declare config and provisions, their files rendered from templates; synced with main (issues of feature 57, 874)

2026-10-16 07:37:43 +00:00
parent 1a2c917abf
commit 9652b2d5ce
771 changed files with 52063 additions and 1774 deletions
@@ -0,0 +1,84 @@
+#!/bin/sh
+# Transparent huge pages as the mesh sets them on this machine (module kernel, novox/hq issue 746).
+# Written by the mesh from this machine's setting transparent-huge-pages and run by
+# mesh-kernel-huge-pages.service: `apply` at boot and whenever the setting changes, `restore` when the
+# unit stops (the module unassigned, or the machine shutting down). Replaced on every push; change the
+# setting, never this file. A change of the setting reloads the unit, which runs `apply` again: the mode
+# moves straight to the new value and never passes back through the one the machine was found with.
+#
+#   huge-pages apply|restore [<the kernel's transparent_hugepage directory> [<this module's state>]]
+#
+# The two directories are arguments only so the module's tests can run this against a stand-in tree.
+set -eu
+
+want='${config:transparent-huge-pages}'
+sys=/sys/kernel/mm/transparent_hugepage
+state='${dir:state}'
+[ $# -ge 2 ] && sys=$2
+[ $# -ge 3 ] && state=$3
+
+case "$want" in
+always | madvise | never) ;;
+*)
+	echo "the setting transparent-huge-pages is '$want'; the kernel takes always, madvise or never" >&2
+	exit 2
+	;;
+esac
+[ -f "$sys/enabled" ] || {
+	echo "this kernel has no $sys/enabled: it was built without transparent huge pages, so there is nothing to set" >&2
+	exit 1
+}
+
+# The mode in force is the word the kernel brackets: "always [madvise] never". A file holding one bare
+# word (the stand-in tree of the tests) is read as that word.
+mode() { sed -n -e 's/.*\[\([a-z]*\)\].*/\1/p' -e t -e 's/^ *\([a-z]*\) *$/\1/p' "$sys/enabled"; }
+
+[ $# -ge 1 ] || set -- usage
+case "$1" in
+apply)
+	now=$(mode)
+	# What the machine had before the mesh first set it, kept once, so `restore` gives it back.
+	[ -s "$state/found" ] || printf '%s\n' "$now" >"$state/found"
+	if [ "$now" = "$want" ]; then
+		echo "transparent huge pages: $want, as set"
+		exit 0
+	fi
+	printf '%s\n' "$want" >"$sys/enabled"
+	got=$(mode)
+	[ "$got" = "$want" ] || {
+		echo "wrote $want to $sys/enabled and the kernel says $got" >&2
+		exit 1
+	}
+	echo "transparent huge pages: $now -> $want"
+	# A file folio already in the page cache keeps its size: the active journal files, mapped by journald
+	# and by every reader, stay in 2 MiB folios until they are archived (issue 746). Rotating starts new
+	# files that are mapped under the new mode. A failed rotation is said and does not fail the setting.
+	# At boot nothing is in huge folios yet, and the persistent journal opens only after this unit: no rotation
+	# while the service manager is still bringing the machine up.
+	booting=$(systemctl is-system-running 2>/dev/null || true)
+	case "$booting" in
+	initializing | starting) echo "the machine is still starting: nothing to rotate yet" ;;
+	*)
+		if [ "$want" != always ] && command -v journalctl >/dev/null 2>&1; then
+			journalctl --rotate || echo "the journal could not be rotated: its active files keep their huge pages until they are archived" >&2
+		fi
+		;;
+	esac
+	;;
+restore)
+	found=$(cat "$state/found" 2>/dev/null || true)
+	case "$found" in
+	always | madvise | never)
+		printf '%s\n' "$found" >"$sys/enabled"
+		echo "transparent huge pages: back to $found, as the machine had them"
+		;;
+	*) echo "transparent huge pages: nothing recorded as found, left at $(mode)" ;;
+	esac
+	# Unassigned or shut down: nothing of the module is kept; the next start records what it finds again.
+	rm -f "$state/found"
+	;;
+*)
+	echo "usage: huge-pages apply|restore [<transparent_hugepage directory> [<state directory>]]" >&2
+	exit 2
+	;;
+esac
@@ -0,0 +1,25 @@
+[Unit]
+Description=Transparent huge pages as the mesh sets them on this machine
+# Module kernel, novox/hq issue 746. Starting this unit sets the mode from the setting
+# transparent-huge-pages; reloading it (the setting changed) sets the new mode; stopping it gives back the
+# mode the machine had before. It runs early in boot, before the services that fill the page cache.
+DefaultDependencies=no
+After=local-fs.target
+Before=sysinit.target shutdown.target
+Conflicts=shutdown.target
+
+[Service]
+Type=oneshot
+RemainAfterExit=yes
+ExecStart=${dir:state}/huge-pages apply
+ExecReload=${dir:state}/huge-pages apply
+ExecStop=${dir:state}/huge-pages restore
+# It writes one file under /sys and its own state, and asks the journal daemon to rotate over its socket.
+ProtectSystem=strict
+ReadWritePaths=${dir:state}
+ProtectHome=yes
+PrivateNetwork=yes
+NoNewPrivileges=yes
+
+[Install]
+WantedBy=sysinit.target