fix for overview panel

internal/hoststats/mem_unix.go

@@ -0,0 +1,61 @@
+//go:build !windows
+
+package hoststats
+
+import (
+	"bufio"
+	"fmt"
+	"os"
+	"strconv"
+	"strings"
+)
+
+// memStats reads host RAM usage from /proc/meminfo. used is derived from
+// MemAvailable (kernel's own "usable without swapping" estimate, accounts
+// for reclaimable cache/buffers) rather than MemTotal-MemFree, which would
+// count page cache as "used" and make a healthy box look starved.
+func memStats() (used, total int64, err error) {
+	f, err := os.Open("/proc/meminfo")
+	if err != nil {
+		return 0, 0, err
+	}
+	defer f.Close()
+
+	var totalKB, availKB int64
+	haveTotal, haveAvail := false, false
+	scanner := bufio.NewScanner(f)
+	for scanner.Scan() {
+		line := scanner.Text()
+		switch {
+		case strings.HasPrefix(line, "MemTotal:"):
+			totalKB, err = parseMeminfoKB(line)
+			haveTotal = err == nil
+		case strings.HasPrefix(line, "MemAvailable:"):
+			availKB, err = parseMeminfoKB(line)
+			haveAvail = err == nil
+		}
+		if haveTotal && haveAvail {
+			break
+		}
+	}
+	if scanErr := scanner.Err(); scanErr != nil {
+		return 0, 0, scanErr
+	}
+	if !haveTotal || !haveAvail {
+		return 0, 0, fmt.Errorf("hoststats: MemTotal/MemAvailable not found in /proc/meminfo")
+	}
+	total = totalKB * 1024
+	used = total - availKB*1024
+	if used < 0 {
+		used = 0
+	}
+	return used, total, nil
+}
+
+func parseMeminfoKB(line string) (int64, error) {
+	fields := strings.Fields(line)
+	if len(fields) < 2 {
+		return 0, fmt.Errorf("hoststats: malformed /proc/meminfo line %q", line)
+	}
+	return strconv.ParseInt(fields[1], 10, 64)
+}