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 157 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 full trace, and redirect stderr to stdout
-  # so the extra tracing won't confuse higher up layers.
-  os.environ['ADB_TRACE'] = 'all'
+  # Restart the adb server with taskset to set a single CPU affinity.
   cmd_helper.RunCmd(['adb', 'kill-server'])
-  cmd_helper.RunCmd(['adb', 'start-server'])
+  cmd_helper.RunCmd(['taskset', '-c', '1', 'adb', 'start-server'])

[frankf, 2013/08/08 21:38:09]

why not -c 0?

[bulach, 2013/08/09 09:15:47]

my bad, I was confused by "man taskset": it says for mask, 0x00000001 is the CPU
#0... that's not the case for -c, thanks for pointing out.

   cmd_helper.RunCmd(['adb', 'root'])
   i = 1
   while not android_commands.GetAttachedDevices():
     time.sleep(i)
     i *= 2
     if i > 10:
       break
 
 
 def main(argv):
@@ skipping 37 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))