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https://issues.apache.org/jira/browse/HADOOP-9194?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=13606610#comment-13606610
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Luke Lu commented on HADOOP-9194:
---------------------------------
Thanks for the patch, Junping! A few things:
# Service level and service class are orthogonal concepts. Different QoS algos
(our current one is basically best effort) can achieve different service level
even for the same service class. The field is really CoS (class of service)
analogous to the DiffServ field in IP see http://www.linktionary.com/q/qos.html
and http://www.linktionary.com/d/diffserv.html for details.
# Make the service class a connection member variable at the server side as
well.
# Add getter/setter for the service class to facilitate testing and future
usage.
# Add a basic test to make sure the service class is being
serialized/transmitted correctly.
> RPC Support for QoS
> -------------------
>
> Key: HADOOP-9194
> URL: https://issues.apache.org/jira/browse/HADOOP-9194
> Project: Hadoop Common
> Issue Type: New Feature
> Components: ipc
> Affects Versions: 2.0.2-alpha
> Reporter: Luke Lu
> Attachments: HADOOP-9194.patch
>
>
> One of the next frontiers of Hadoop performance is QoS (Quality of Service).
> We need QoS support to fight the inevitable "buffer bloat" (including various
> queues, which are probably necessary for throughput) in our software stack.
> This is important for mixed workload with different latency and throughput
> requirements (e.g. OLTP vs OLAP, batch and even compaction I/O) against the
> same DFS.
> Any potential bottleneck will need to be managed by QoS mechanisms, starting
> with RPC.
> How about adding a one byte DS (differentiated services) field (a la the
> 6-bit DS field in IP header) in the RPC header to facilitate the QoS
> mechanisms (in separate JIRAs)? The byte at a fixed offset (how about 0?) of
> the header is helpful for implementing high performance QoS mechanisms in
> switches (software or hardware) and servers with minimum decoding effort.
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