copied cpu_stat from pwnagotchi/__index__.py, and calculate load since previous call, instead of sampling 0.1s while updating

On Pi0 instead of always seeing 100%, I see 40-80% typical, which seems more in line with what is happening on the system

pwnagotchi/plugins/default/memtemp.py

@@ -41,6 +41,7 @@ class MemTemp(plugins.Plugin):
     ALLOWED_FIELDS = {
         'mem': 'mem_usage',
         'cpu': 'cpu_load',
+        'cpus': 'cpu_load_since',
         'temp': 'cpu_temp',
         'freq': 'cpu_freq'
     }
@@ -50,6 +51,7 @@ class MemTemp(plugins.Plugin):
     FIELD_WIDTH = 4
 
     def on_loaded(self):
+        self._last_cpu_load = self._cpu_stat()
         logging.info("memtemp plugin loaded.")
 
     def mem_usage(self):
@@ -58,6 +60,28 @@ class MemTemp(plugins.Plugin):
     def cpu_load(self):
         return f"{int(pwnagotchi.cpu_load() * 100)}%"
 
+    def _cpu_stat(self):
+        """
+        Returns the splitted first line of the /proc/stat file
+        """
+        with open('/proc/stat', 'rt') as fp:
+            return list(map(int,fp.readline().split()[1:]))
+
+    def cpu_load_since(self):
+        """
+        Returns the % load, since last time called
+        """
+        parts0 = self._cpu_stat()
+        parts1 = self._last_cpu_load
+        self._last_cpu_load = parts0
+
+        parts_diff = [p1 - p0 for (p0, p1) in zip(parts0, parts1)]
+        user, nice, sys, idle, iowait, irq, softirq, steal, _guest, _guest_nice = parts_diff
+        idle_sum = idle + iowait
+        non_idle_sum = user + nice + sys + irq + softirq + steal
+        total = idle_sum + non_idle_sum
+        return f"{int(non_idle_sum / total * 100)}%"
+
     def cpu_temp(self):
         if self.options['scale'] == "fahrenheit":
             temp = (pwnagotchi.temperature() * 9 / 5) + 32