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Colin Patrick McCabe commented on HDFS-4953: -------------------------------------------- I'd also like to add that RHEL5 is 6 years old, and most Hadoop users have migrated away from it already. There are a few new features coming down the pipe, like resource management via cgroups, that are not going to be supported on RHEL5. > 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: 2.3.0 > Reporter: Colin Patrick McCabe > Assignee: Colin Patrick McCabe > Attachments: benchmark.png, HDFS-4953.001.patch, HDFS-4953.002.patch, > HDFS-4953.003.patch, HDFS-4953.004.patch, HDFS-4953.005.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