old_contents: #!/usr/bin/env python
  # Copyright (c) 2012 Cloudera, Inc. All rights reserved.
  #
  # Licensed under the Apache License, Version 2.0 (the "License");
  # you may not use this file except in compliance with the License.
  # You may obtain a copy of the License at
  #
  # http://www.apache.org/licenses/LICENSE-2.0
  #
  # Unless required by applicable law or agreed to in writing, software
  # distributed under the License is distributed on an "AS IS" BASIS,
  # WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
  # See the License for the specific language governing permissions and
  # limitations under the License.
  
  from tests.util.cluster_controller import ClusterController
  from tests.benchmark.plugins import Plugin
  
  class ClearBufferCache(Plugin):
    """Plugin that clears the buffer cache before a query is run."""
  
    __name__ = "ClearBufferCache"
  
    def __init__(self, *args, **kwargs):
      self.cluster_controller = ClusterController(*args, **kwargs)
      Plugin.__init__(self, *args, **kwargs)
  
    def run_pre_hook(self, context=None):
      cmd = "sysctl -w vm.drop_caches=3 vm.drop_caches=0"
      self.cluster_controller.run_cmd(cmd)
  
new_contents: #!/usr/bin/env python
  # Copyright (c) 2012 Cloudera, Inc. All rights reserved.
  #
  # Licensed under the Apache License, Version 2.0 (the "License");
  # you may not use this file except in compliance with the License.
  # You may obtain a copy of the License at
  #
  # http://www.apache.org/licenses/LICENSE-2.0
  #
  # Unless required by applicable law or agreed to in writing, software
  # distributed under the License is distributed on an "AS IS" BASIS,
  # WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
  # See the License for the specific language governing permissions and
  # limitations under the License.
  
  from tests.util.cluster_controller import ClusterController
  from tests.benchmark.plugins import Plugin
  
  class ClearBufferCache(Plugin):
    """Plugin that clears the buffer cache before a query is run."""
  
    __name__ = "ClearBufferCache"
  
    def __init__(self, *args, **kwargs):
      self.cluster_controller = ClusterController(*args, **kwargs)
      Plugin.__init__(self, *args, **kwargs)
  
    def run_pre_hook(self, context=None):
      # Drop the page cache (drop_caches=1). We'll leave the inodes and dentries
      # since that is not what we are testing and it causes excessive performance
      # variability.
      cmd = "sysctl -w vm.drop_caches=1 vm.drop_caches=0"
      self.cluster_controller.run_cmd(cmd)
  
subject: Update clear buffer cache plugin to only flush page cache.