Show memory stats in debug

cmd/sing-box/debug_linux.go

@@ -0,0 +1,25 @@
+//go:build debug
+
+package main
+
+import (
+	"runtime"
+	"syscall"
+)
+
+func rusageMaxRSS() float64 {
+	ru := syscall.Rusage{}
+	err := syscall.Getrusage(syscall.RUSAGE_SELF, &ru)
+	if err != nil {
+		return 0
+	}
+
+	rss := float64(ru.Maxrss)
+	if runtime.GOOS == "darwin" || runtime.GOOS == "ios" {
+		rss /= 1 << 20 // ru_maxrss is bytes on darwin
+	} else {
+		// ru_maxrss is kilobytes elsewhere (linux, openbsd, etc)
+		rss /= 1 << 10
+	}
+	return rss
+}