def METHOD_NAME(benchmark_spec):
  """Run YCSB with against MongoDB.
  Args:
    benchmark_spec: The benchmark specification. Contains all data that is
        required to run the benchmark.
  Returns:
    A list of sample.Sample objects.
  """
  kwargs = {
      'mongodb.url': benchmark_spec.mongodb_url,
      'mongodb.writeConcern': FLAGS.mongodb_writeconcern}
  samples = list(benchmark_spec.executor.LoadAndRun(
      benchmark_spec.vm_groups['clients'],
      load_kwargs=kwargs, run_kwargs=kwargs))
  if FLAGS.mongodb_readahead_kb is not None:
    for s in samples:
      s.metadata['readahdead_kb'] = FLAGS.mongodb_readahead_kb
  return samples