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Hadoop QA commented on HDFS-4953: --------------------------------- {color:red}-1 overall{color}. Here are the results of testing the latest attachment http://issues.apache.org/jira/secure/attachment/12592045/0001-HDFS-4953.patch against trunk revision . {color:red}-1 patch{color}. The patch command could not apply the patch. Console output: https://builds.apache.org/job/PreCommit-HDFS-Build/4646//console This message is automatically generated. > enable HDFS local reads via mmap > -------------------------------- > > Key: HDFS-4953 > URL: https://issues.apache.org/jira/browse/HDFS-4953 > Project: Hadoop HDFS > Issue Type: New Feature > Affects Versions: 2.2.0 > Reporter: Colin Patrick McCabe > Assignee: Colin Patrick McCabe > Attachments: 0001-HDFS-4953.patch > > > Currently, the short-circuit local read pathway allows HDFS clients to access > files directly without going through the DataNode. However, all of these > reads involve a copy at the operating system level, since they rely on the > read() / pread() / etc family of kernel interfaces. > We would like to enable HDFS to read local files via mmap. This would enable > truly zero-copy reads. > In the initial implementation, zero-copy reads will only be performed when > checksums were disabled. Later, we can use the DataNode's cache awareness to > only perform zero-copy reads when we know that checksum has already been > verified. -- This message is automatically generated by JIRA. If you think it was sent incorrectly, please contact your JIRA administrators For more information on JIRA, see: http://www.atlassian.com/software/jira