CPU budget (#32335)

* cpu budget

* comment

* new line

selfdrive/test/test_onroad.py

@@ -27,8 +27,15 @@ from openpilot.selfdrive.test.helpers import set_params_enabled, release_only
 from openpilot.system.hardware.hw import Paths
 from openpilot.tools.lib.logreader import LogReader
 
-# Baseline CPU usage by process
+"""
+CPU usage budget
+* each process is entitled to at least 8%
+* total CPU usage of openpilot (sum(PROCS.values())
+  should not exceed MAX_TOTAL_CPU
+"""
+MAX_TOTAL_CPU = 250.  # total for all 8 cores
 PROCS = {
+  # Baseline CPU usage by process
   "selfdrive.controls.controlsd": 46.0,
   "./loggerd": 14.0,
   "./encoderd": 17.0,
@@ -274,6 +281,7 @@ class TestOnroad(unittest.TestCase):
       result += f"{proc_name.ljust(35)}  {cpu_usage:5.2f}% ({exp}%) {err}\n"
       if len(err) > 0:
         cpu_ok = False
+    result += "------------------------------------------------\n"
 
     # Ensure there's no missing procs
     all_procs = {p.name for p in self.service_msgs['managerState'][0].managerState.processes if p.shouldBeRunning}
@@ -281,7 +289,14 @@ class TestOnroad(unittest.TestCase):
       with self.subTest(proc=p):
         assert any(p in pp for pp in PROCS.keys()), f"Expected CPU usage missing for {p}"
 
-    result += "------------------------------------------------\n"
+    # total CPU check
+    procs_tot = sum([(max(x) if isinstance(x, tuple) else x) for x in PROCS.values()])
+    with self.subTest(name="total CPU"):
+      assert procs_tot < MAX_TOTAL_CPU, "Total CPU budget exceeded"
+    result +=  "------------------------------------------------\n"
+    result += f"Total allocated CPU usage is {procs_tot}%, budget is {MAX_TOTAL_CPU}%, {MAX_TOTAL_CPU-procs_tot:.1f}% left\n"
+    result +=  "------------------------------------------------\n"
+
     print(result)
 
     self.assertTrue(cpu_ok)