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Posted to hdfs-commits@hadoop.apache.org by to...@apache.org on 2012/07/23 18:28:05 UTC
svn commit: r1364699 - in
/hadoop/common/branches/branch-2/hadoop-hdfs-project/hadoop-hdfs:
CHANGES.txt src/main/java/org/apache/hadoop/hdfs/DFSConfigKeys.java
src/main/resources/hdfs-default.xml
Author: todd
Date: Mon Jul 23 16:28:04 2012
New Revision: 1364699
URL: http://svn.apache.org/viewvc?rev=1364699&view=rev
Log:
HDFS-3697. Enable fadvise readahead by default. Contributed by Todd Lipcon.
Modified:
hadoop/common/branches/branch-2/hadoop-hdfs-project/hadoop-hdfs/CHANGES.txt
hadoop/common/branches/branch-2/hadoop-hdfs-project/hadoop-hdfs/src/main/java/org/apache/hadoop/hdfs/DFSConfigKeys.java
hadoop/common/branches/branch-2/hadoop-hdfs-project/hadoop-hdfs/src/main/resources/hdfs-default.xml
Modified: hadoop/common/branches/branch-2/hadoop-hdfs-project/hadoop-hdfs/CHANGES.txt
URL: http://svn.apache.org/viewvc/hadoop/common/branches/branch-2/hadoop-hdfs-project/hadoop-hdfs/CHANGES.txt?rev=1364699&r1=1364698&r2=1364699&view=diff
==============================================================================
--- hadoop/common/branches/branch-2/hadoop-hdfs-project/hadoop-hdfs/CHANGES.txt (original)
+++ hadoop/common/branches/branch-2/hadoop-hdfs-project/hadoop-hdfs/CHANGES.txt Mon Jul 23 16:28:04 2012
@@ -181,6 +181,8 @@ Release 2.0.1-alpha - UNRELEASED
HDFS-3110. Use directRead API to reduce the number of buffer copies in
libhdfs (Henry Robinson via todd)
+ HDFS-3697. Enable fadvise readahead by default. (todd)
+
BUG FIXES
HDFS-3385. The last block of INodeFileUnderConstruction is not
Modified: hadoop/common/branches/branch-2/hadoop-hdfs-project/hadoop-hdfs/src/main/java/org/apache/hadoop/hdfs/DFSConfigKeys.java
URL: http://svn.apache.org/viewvc/hadoop/common/branches/branch-2/hadoop-hdfs-project/hadoop-hdfs/src/main/java/org/apache/hadoop/hdfs/DFSConfigKeys.java?rev=1364699&r1=1364698&r2=1364699&view=diff
==============================================================================
--- hadoop/common/branches/branch-2/hadoop-hdfs-project/hadoop-hdfs/src/main/java/org/apache/hadoop/hdfs/DFSConfigKeys.java (original)
+++ hadoop/common/branches/branch-2/hadoop-hdfs-project/hadoop-hdfs/src/main/java/org/apache/hadoop/hdfs/DFSConfigKeys.java Mon Jul 23 16:28:04 2012
@@ -74,7 +74,7 @@ public class DFSConfigKeys extends Commo
public static final String DFS_DATANODE_BALANCE_BANDWIDTHPERSEC_KEY = "dfs.datanode.balance.bandwidthPerSec";
public static final long DFS_DATANODE_BALANCE_BANDWIDTHPERSEC_DEFAULT = 1024*1024;
public static final String DFS_DATANODE_READAHEAD_BYTES_KEY = "dfs.datanode.readahead.bytes";
- public static final long DFS_DATANODE_READAHEAD_BYTES_DEFAULT = 0;
+ public static final long DFS_DATANODE_READAHEAD_BYTES_DEFAULT = 4 * 1024 * 1024; // 4MB
public static final String DFS_DATANODE_DROP_CACHE_BEHIND_WRITES_KEY = "dfs.datanode.drop.cache.behind.writes";
public static final boolean DFS_DATANODE_DROP_CACHE_BEHIND_WRITES_DEFAULT = false;
public static final String DFS_DATANODE_SYNC_BEHIND_WRITES_KEY = "dfs.datanode.sync.behind.writes";
Modified: hadoop/common/branches/branch-2/hadoop-hdfs-project/hadoop-hdfs/src/main/resources/hdfs-default.xml
URL: http://svn.apache.org/viewvc/hadoop/common/branches/branch-2/hadoop-hdfs-project/hadoop-hdfs/src/main/resources/hdfs-default.xml?rev=1364699&r1=1364698&r2=1364699&view=diff
==============================================================================
--- hadoop/common/branches/branch-2/hadoop-hdfs-project/hadoop-hdfs/src/main/resources/hdfs-default.xml (original)
+++ hadoop/common/branches/branch-2/hadoop-hdfs-project/hadoop-hdfs/src/main/resources/hdfs-default.xml Mon Jul 23 16:28:04 2012
@@ -715,6 +715,80 @@
</property>
<property>
+ <name>dfs.datanode.readahead.bytes</name>
+ <value>4193404</value>
+ <description>
+ While reading block files, if the Hadoop native libraries are available,
+ the datanode can use the posix_fadvise system call to explicitly
+ page data into the operating system buffer cache ahead of the current
+ reader's position. This can improve performance especially when
+ disks are highly contended.
+
+ This configuration specifies the number of bytes ahead of the current
+ read position which the datanode will attempt to read ahead. This
+ feature may be disabled by configuring this property to 0.
+
+ If the native libraries are not available, this configuration has no
+ effect.
+ </description>
+</property>
+
+<property>
+ <name>dfs.datanode.drop.cache.behind.reads</name>
+ <value>false</value>
+ <description>
+ In some workloads, the data read from HDFS is known to be significantly
+ large enough that it is unlikely to be useful to cache it in the
+ operating system buffer cache. In this case, the DataNode may be
+ configured to automatically purge all data from the buffer cache
+ after it is delivered to the client. This behavior is automatically
+ disabled for workloads which read only short sections of a block
+ (e.g HBase random-IO workloads).
+
+ This may improve performance for some workloads by freeing buffer
+ cache spage usage for more cacheable data.
+
+ If the Hadoop native libraries are not available, this configuration
+ has no effect.
+ </description>
+</property>
+
+<property>
+ <name>dfs.datanode.drop.cache.behind.writes</name>
+ <value>false</value>
+ <description>
+ In some workloads, the data written to HDFS is known to be significantly
+ large enough that it is unlikely to be useful to cache it in the
+ operating system buffer cache. In this case, the DataNode may be
+ configured to automatically purge all data from the buffer cache
+ after it is written to disk.
+
+ This may improve performance for some workloads by freeing buffer
+ cache spage usage for more cacheable data.
+
+ If the Hadoop native libraries are not available, this configuration
+ has no effect.
+ </description>
+</property>
+
+<property>
+ <name>dfs.datanode.sync.behind.writes</name>
+ <value>false</value>
+ <description>
+ If this configuration is enabled, the datanode will instruct the
+ operating system to enqueue all written data to the disk immediately
+ after it is written. This differs from the usual OS policy which
+ may wait for up to 30 seconds before triggering writeback.
+
+ This may improve performance for some workloads by smoothing the
+ IO profile for data written to disk.
+
+ If the Hadoop native libraries are not available, this configuration
+ has no effect.
+ </description>
+</property>
+
+<property>
<name>dfs.client.failover.max.attempts</name>
<value>15</value>
<description>