Add the kernel module: transparent huge pages set per machine (hq issue 746)

With THP 'always' journald's mmapped journal files sit in 2 MiB folios, so each small journal write dirties and writes back 2 MiB; on the control node that saturated the root mirror holding the bus store and the store, and the controller lost its lease. The module sets the mode from a per-machine setting (default always, the kernel's own, so assigning it changes nothing until a machine sets madvise), verifies it took, rotates the journal once so new files are mapped under the new mode, gives back what it found when stopped, and serves kernel_huge_pages to measure file_thp per unit.
2026-10-14 23:31:13 +02:00
parent 0f76b6e232
commit 3a84044ece
10 changed files with 855 additions and 0 deletions
@@ -0,0 +1,79 @@
+package main
+
+import (
+	"encoding/json"
+	"os"
+	"testing"
+)
+
+type resource map[string]any
+
+type manifestShape struct {
+	Module       string                    `json:"module"`
+	Capabilities []string                  `json:"capabilities"`
+	Settings     map[string]map[string]any `json:"settings"`
+	Tools        []string                  `json:"tools"`
+	Resources    []resource                `json:"resources"`
+	Build        struct {
+		Artifacts []map[string]any `json:"artifacts"`
+	} `json:"build"`
+}
+
+func manifest(t *testing.T) manifestShape {
+	t.Helper()
+	raw, err := os.ReadFile("../../module.json")
+	if err != nil {
+		t.Fatal(err)
+	}
+	var m manifestShape
+	if err := json.Unmarshal(raw, &m); err != nil {
+		t.Fatal(err)
+	}
+	return m
+}
+
+func (m manifestShape) resource(t *testing.T, id string) resource {
+	t.Helper()
+	for _, r := range m.Resources {
+		if r["id"] == id {
+			return r
+		}
+	}
+	t.Fatalf("no resource %s", id)
+	return nil
+}
+
+// TestToolsAreTheManifests holds the served tools and the manifest's list to one another, and the
+// bundle to the shape the builder compiles and the runtime loads.
+func TestToolsAreTheManifests(t *testing.T) {
+	m := manifest(t)
+	names := map[string]bool{}
+	for _, tool := range tools(&Machine{Root: t.TempDir()}) {
+		if names[tool.Name] {
+			t.Errorf("%s is served twice", tool.Name)
+		}
+		names[tool.Name] = true
+	}
+	for _, want := range m.Tools {
+		if !names[want] {
+			t.Errorf("the manifest lists %s and the bundle does not serve it", want)
+		}
+		delete(names, want)
+	}
+	if len(names) != 0 {
+		t.Errorf("served and not listed: %v", names)
+	}
+	var tools map[string]any
+	for _, a := range m.Build.Artifacts {
+		if a["name"] == "tools" {
+			tools = a
+		}
+	}
+	if tools == nil || tools["kind"] != "bundle" || tools["language"] != "go" || tools["system"] != "arch" ||
+		tools["from"] != "cmd/"+binaryName || tools["binary"] != binaryName {
+		t.Fatalf("the tools artifact: %v", tools)
+	}
+	if loads, _ := tools["loads"].([]any); len(loads) != 1 || loads[0] != binaryName {
+		t.Fatalf("loads: %v", tools["loads"])
+	}
+}