Android: uses settask to enable CPU affinity for ADB.

build/android/bb_run_sharded_steps.py

 #!/usr/bin/env python
 #
 # Copyright (c) 2012 The Chromium Authors. All rights reserved.
 # Use of this source code is governed by a BSD-style license that can be
 # found in the LICENSE file.
 
 """Helper script to shard build bot steps and save results to disk.
 
 Our buildbot infrastructure requires each slave to run steps serially.
 This is sub-optimal for android, where these steps can run independently on
@@ skipping 36 matching lines @@
 import json
 import logging
 import multiprocessing
 import optparse
 import pexpect
 import pickle
 import os
 import signal
 import shutil
 import sys
+import time
 
 from pylib import android_commands
 from pylib import cmd_helper
 from pylib import constants
 from pylib import forwarder
 from pylib import ports
 
 
 _OUTPUT_DIR = os.path.join(constants.DIR_SOURCE_ROOT, 'out', 'step_results')
 
@@ skipping 100 matching lines @@
   for retry in range(5):
     for server in ['lighttpd', 'web-page-replay']:
       pids = cmd_helper.GetCmdOutput(['pgrep', '-f', server])
       pids = [pid.strip() for pid in pids.split('\n') if pid.strip()]
       for pid in pids:
         try:
           logging.warning('Killing %s %s', server, pid)
           os.kill(int(pid), signal.SIGQUIT)
         except Exception as e:
           logging.warning('Failed killing %s %s %s', server, pid, e)
+  # Restart the adb server with taskset to set a single CPU affinity.
+  cmd_helper.RunCmd(['adb', 'kill-server'])
+  cmd_helper.RunCmd(['taskset', '-c', '0', 'adb', 'start-server'])
+  cmd_helper.RunCmd(['taskset', '-c', '0', 'adb', 'root'])
+  i = 1
+  while not android_commands.GetAttachedDevices():
+    time.sleep(i)
+    i *= 2
+    if i > 10:
+      break
 
 
 def main(argv):
   parser = optparse.OptionParser()
   parser.add_option('-s', '--steps',
                     help='A JSON file containing all the steps to be '
                          'sharded.')
   parser.add_option('--flaky_steps',
                     help='A JSON file containing steps that are flaky and '
                          'will have its exit code ignored.')
@@ skipping 30 matching lines @@
     steps = json.load(f)
   flaky_steps = []
   if options.flaky_steps:
     with file(options.flaky_steps, 'r') as f:
       flaky_steps = json.load(f)
   return _RunShardedSteps(steps, flaky_steps, devices)
 
 
 if __name__ == '__main__':
   sys.exit(main(sys.argv))