oeqa: Add sync call to command execution

We previously put a sync call into devtool to try and combat the bitbake
timeout issues on the autobuilder. It isn't enough as the timeouts occur
mid test. They are also occurring on non-devtool tests.

Add in sync calls around command execution instead.

(From OE-Core rev: ceca5ed121e2b54415a7ab3a217882e4ea86923a)

Signed-off-by: Richard Purdie <richard.purdie@linuxfoundation.org>

meta/lib/oeqa/utils/commands.py

@@ -167,7 +167,7 @@ class Result(object):
     pass
 
 
-def runCmd(command, ignore_status=False, timeout=None, assert_error=True,
+def runCmd(command, ignore_status=False, timeout=None, assert_error=True, sync=True,
           native_sysroot=None, limit_exc_output=0, output_log=None, **options):
     result = Result()
 
@@ -184,6 +184,12 @@ def runCmd(command, ignore_status=False, timeout=None, assert_error=True,
     cmd = Command(command, timeout=timeout, output_log=output_log, **options)
     cmd.run()
 
+    # tests can be heavy on IO and if bitbake can't write out its caches, we see timeouts.
+    # call sync around the tests to ensure the IO queue doesn't get too large, taking any IO
+    # hit here rather than in bitbake shutdown.
+    if sync:
+        os.system("sync")
+
     result.command = command
     result.status = cmd.status
     result.output = cmd.output