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  1. Hadoop HDFS
  2. HDFS-2465

Add HDFS support for fadvise readahead and drop-behind

    Details

    • Type: Improvement
    • Status: Closed
    • Priority: Major
    • Resolution: Fixed
    • Affects Version/s: 0.23.0
    • Fix Version/s: 0.23.0, 1.1.0
    • Component/s: datanode, performance
    • Labels:
      None
    • Target Version/s:
    • Hadoop Flags:
      Reviewed
    • Release Note:
      Hide
      HDFS now has the ability to use posix_fadvise and sync_data_range syscalls to manage the OS buffer cache. This support is currently considered experimental, and may be enabled by configuring the following keys:
      dfs.datanode.drop.cache.behind.writes - set to true to drop data out of the buffer cache after writing
      dfs.datanode.drop.cache.behind.reads - set to true to drop data out of the buffer cache when performing sequential reads
      dfs.datanode.sync.behind.writes - set to true to trigger dirty page writeback immediately after writing data
      dfs.datanode.readahead.bytes - set to a non-zero value to trigger readahead for sequential reads
      Show
      HDFS now has the ability to use posix_fadvise and sync_data_range syscalls to manage the OS buffer cache. This support is currently considered experimental, and may be enabled by configuring the following keys: dfs.datanode.drop.cache.behind.writes - set to true to drop data out of the buffer cache after writing dfs.datanode.drop.cache.behind.reads - set to true to drop data out of the buffer cache when performing sequential reads dfs.datanode.sync.behind.writes - set to true to trigger dirty page writeback immediately after writing data dfs.datanode.readahead.bytes - set to a non-zero value to trigger readahead for sequential reads

      Description

      This is the HDFS side of HADOOP-7714. The initial implementation is heuristic based and should be considered experimental, as discussed in the parent JIRA. It should be off by default until better heuristics, APIs, and tuning experience is developed.

        Attachments

        1. HDFS-2465.branch-1.patch
          16 kB
          Brandon Li
        2. hdfs-2465.txt
          16 kB
          Todd Lipcon
        3. hdfs-2465.txt
          16 kB
          Todd Lipcon
        4. hdfs-2465.txt
          16 kB
          Todd Lipcon
        5. hdfs-2465.txt
          16 kB
          Todd Lipcon

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              • Assignee:
                tlipcon Todd Lipcon
                Reporter:
                tlipcon Todd Lipcon
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                Dates

                • Created:
                  Updated:
                  Resolved: