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https://issues.apache.org/jira/browse/HBASE-13259?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=15159049#comment-15159049
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Hudson commented on HBASE-13259:
--------------------------------
FAILURE: Integrated in HBase-Trunk_matrix #730 (See
[https://builds.apache.org/job/HBase-Trunk_matrix/730/])
HBASE-13259 mmap() based BucketCache IOEngine (Zee Chen & Ram) (ramkrishna: rev
3ba1a7fd23f0b0ca06cf7a9a04cb45975e1c7d91)
*
hbase-server/src/main/java/org/apache/hadoop/hbase/io/hfile/bucket/ByteBufferIOEngine.java
*
hbase-server/src/main/java/org/apache/hadoop/hbase/io/hfile/bucket/FileMmapEngine.java
*
hbase-server/src/main/java/org/apache/hadoop/hbase/io/hfile/bucket/BucketCache.java
* hbase-common/src/main/java/org/apache/hadoop/hbase/util/ByteBufferArray.java
*
hbase-common/src/test/java/org/apache/hadoop/hbase/util/TestByteBufferArray.java
*
hbase-server/src/test/java/org/apache/hadoop/hbase/io/hfile/bucket/TestFileMmapEngine.java
*
hbase-common/src/main/java/org/apache/hadoop/hbase/util/ByteBufferAllocator.java
> mmap() based BucketCache IOEngine
> ---------------------------------
>
> Key: HBASE-13259
> URL: https://issues.apache.org/jira/browse/HBASE-13259
> Project: HBase
> Issue Type: New Feature
> Components: BlockCache
> Affects Versions: 0.98.10
> Reporter: Zee Chen
> Assignee: Zee Chen
> Priority: Critical
> Fix For: 2.0.0
>
> Attachments: HBASE-13259-v2.patch, HBASE-13259.patch,
> HBASE-13259_v3.patch, HBASE-13259_v4.patch, HBASE-13259_v5.patch,
> HBASE-13259_v6.patch, ioread-1.svg, mmap-0.98-v1.patch, mmap-1.svg,
> mmap-trunk-v1.patch
>
>
> Of the existing BucketCache IOEngines, FileIOEngine uses pread() to copy data
> from kernel space to user space. This is a good choice when the total working
> set size is much bigger than the available RAM and the latency is dominated
> by IO access. However, when the entire working set is small enough to fit in
> the RAM, using mmap() (and subsequent memcpy()) to move data from kernel
> space to user space is faster. I have run some short keyval gets tests and
> the results indicate a reduction of 2%-7% of kernel CPU on my system,
> depending on the load. On the gets, the latency histograms from mmap() are
> identical to those from pread(), but peak throughput is close to 40% higher.
> This patch modifies ByteByfferArray to allow it to specify a backing file.
> Example for using this feature: set hbase.bucketcache.ioengine to
> mmap:/dev/shm/bucketcache.0 in hbase-site.xml.
> Attached perf measured CPU usage breakdown in flames graph.
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