Revert^2 "Use only half of the cores in testrunner by default on target."

This is what we currently do on buildbots to avoid timeouts.
Set the appropriate default here and let the buildbots use the default.

This will make it device independent so we don't have to hard-code the
value on buildbot (in case device with different core count is used).

It will also make it easier to investigate the timeouts in the future,
hopefully allowing us fully utilize the devices on the build bots.

Allow the user to specify -j0 to explicitly use the default.

Bug: 142039427
Test: test.py on target
Change-Id: Ic595b411f6e5be51ca407fdb275d2481e44052b5

1 files changed, 24 insertions, 20 deletions

diff --git a/test/testrunner/testrunner.py b/test/testrunner/testrunner.py
index 23bd37de7e..89cfc30443 100755
--- a/test/testrunner/testrunner.py
+++ b/test/testrunner/testrunner.py
@@ -127,7 +127,7 @@ failed_tests = []
 skipped_tests = []
 
 # Flags
-n_thread = -1
+n_thread = 0
 total_test_count = 0
 verbose = False
 dry_run = False
@@ -272,11 +272,12 @@ def setup_test_env():
     _user_input_variants['address_sizes_target']['target'] = _user_input_variants['address_sizes']
 
   global n_thread
-  if n_thread == -1:
+  if n_thread == 0:
     if 'target' in _user_input_variants['target']:
-      n_thread = get_default_threads('target')
+      # Use only half of the cores since fully loading the device tends to lead to timeouts.
+      n_thread = get_target_cpu_count() // 2
     else:
-      n_thread = get_default_threads('host')
+      n_thread = get_host_cpu_count()
     print_text("Concurrency: " + str(n_thread) + "\n")
 
   global extra_arguments
@@ -1002,22 +1003,24 @@ def parse_test_name(test_name):
   return {parsed[12]}
 
 
-def get_default_threads(target):
-  if target == 'target':
-    adb_command = 'adb shell cat /sys/devices/system/cpu/present'
-    cpu_info_proc = subprocess.Popen(adb_command.split(), stdout=subprocess.PIPE)
-    cpu_info = cpu_info_proc.stdout.read()
-    if type(cpu_info) is bytes:
-      cpu_info = cpu_info.decode('utf-8')
-    cpu_info_regex = r'\d*-(\d*)'
-    match = re.match(cpu_info_regex, cpu_info)
-    if match:
-      return int(match.group(1))
-    else:
-      raise ValueError('Unable to predict the concurrency for the target. '
-                       'Is device connected?')
+def get_target_cpu_count():
+  adb_command = 'adb shell cat /sys/devices/system/cpu/present'
+  cpu_info_proc = subprocess.Popen(adb_command.split(), stdout=subprocess.PIPE)
+  cpu_info = cpu_info_proc.stdout.read()
+  if type(cpu_info) is bytes:
+    cpu_info = cpu_info.decode('utf-8')
+  cpu_info_regex = r'\d*-(\d*)'
+  match = re.match(cpu_info_regex, cpu_info)
+  if match:
+    return int(match.group(1)) + 1  # Add one to convert from "last-index" to "count"
   else:
-    return multiprocessing.cpu_count()
+    raise ValueError('Unable to predict the concurrency for the target. '
+                     'Is device connected?')
+
+
+def get_host_cpu_count():
+  return multiprocessing.cpu_count()
+
 
 def parse_option():
   global verbose
@@ -1041,7 +1044,8 @@ def parse_option():
   parser.add_argument('-t', '--test', action='append', dest='tests', help='name(s) of the test(s)')
   global_group = parser.add_argument_group('Global options',
                                            'Options that affect all tests being run')
-  global_group.add_argument('-j', type=int, dest='n_thread')
+  global_group.add_argument('-j', type=int, dest='n_thread', help="""Number of CPUs to use.
+                            Defaults to half of CPUs on target and all CPUs on host.""")
   global_group.add_argument('--timeout', default=timeout, type=int, dest='timeout')
   global_group.add_argument('--verbose', '-v', action='store_true', dest='verbose')
   global_group.add_argument('--dry-run', action='store_true', dest='dry_run')