Liang Xie created HDFS-6109:
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Summary: let sync_file_range() system call run in backgroud
Key: HDFS-6109
URL: https://issues.apache.org/jira/browse/HDFS-6109
Project: Hadoop HDFS
Issue Type: Improvement
Components: datanode
Affects Versions: 2.3.0, 3.0.0
Reporter: Liang Xie
Assignee: Liang Xie
Through we passed SYNC_FILE_RANGE_WRITE to sync_file_range, to make it as
asynchronous as possible, it still could be blocked, e.g. the os io request
queue is full.
Since we use sync_file_range just as a page cache advisor role:) it doesn't
decide or guarantee the real durability, it would be nice if we could run it in
backgroud. At least my test log showed, a few sync_file_range calls still cost
tens of ms or more, due to the happened location is in the critical write
path(BlockReceiver class), from a upper view, like HBase application, will
"hung" tens of ms as well during Hlog syncing.
Generally speaking, the patch could not improve too much, but, better than
before, right ? :)
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