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Date: Wed, 29 Jul 2015 00:56:05 +0000 (UTC)
From: "He Tianyi (JIRA)" <jira@apache.org>
To: hdfs-issues@hadoop.apache.org
Message-ID: <JIRA.12849618.1438091484000.313884.1438131365369@Atlassian.JIRA>
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 <JIRA.12849618.1438091484993@arcas>
Subject: [jira] [Commented] (HDFS-8829) DataNode sets SO_RCVBUF explicitly
 is disabling tcp auto-tuning
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    [ https://issues.apache.org/jira/browse/HDFS-8829?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=14645305#comment-14645305 ] 

He Tianyi commented on HDFS-8829:
---------------------------------

This affects pipeline throughput, and I've observed a 30% performance gain with tcp auto-tuning enabled. 
(since 128KB window size is not always optimal)

Could be particularly useful with SSD drives (where disk throughput may be greater than net throughput).


> DataNode sets SO_RCVBUF explicitly is disabling tcp auto-tuning
> ---------------------------------------------------------------
>
>                 Key: HDFS-8829
>                 URL: https://issues.apache.org/jira/browse/HDFS-8829
>             Project: Hadoop HDFS
>          Issue Type: Improvement
>          Components: datanode
>    Affects Versions: 2.3.0, 2.6.0
>            Reporter: He Tianyi
>            Assignee: kanaka kumar avvaru
>
> {code:java}
>   private void initDataXceiver(Configuration conf) throws IOException {
>     // find free port or use privileged port provided
>     TcpPeerServer tcpPeerServer;
>     if (secureResources != null) {
>       tcpPeerServer = new TcpPeerServer(secureResources);
>     } else {
>       tcpPeerServer = new TcpPeerServer(dnConf.socketWriteTimeout,
>           DataNode.getStreamingAddr(conf));
>     }
>     tcpPeerServer.setReceiveBufferSize(HdfsConstants.DEFAULT_DATA_SOCKET_SIZE);
> {code}
> The last line sets SO_RCVBUF explicitly, thus disabling tcp auto-tuning on some system.
> Shall we make this behavior configurable?


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