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https://issues.apache.org/jira/browse/HBASE-13259?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel
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Zee Chen updated HBASE-13259:
-----------------------------
Description:
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.
was:
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.
> 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
> Attachments: 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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