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Date: Tue, 4 Jan 2011 12:04:47 -0500 (EST)
From: "Jonathan Ellis (JIRA)" <jira@apache.org>
To: commits@cassandra.apache.org
Subject: [jira] Commented: (CASSANDRA-1714) zero-copy reads
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    [ https://issues.apache.org/jira/browse/CASSANDRA-1714?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=12977346#action_12977346 ] 

Jonathan Ellis commented on CASSANDRA-1714:
-------------------------------------------

ICS2 FileChannel will *only* help multinode clusters.  So if you're not seeing any speed difference on a single node cluster, then that's going to be a waste of time.

Let's speed up local reads first, then worry about the filechannel serialization later.  And if it turns out we can't do the first, then let's not bother with the second.

> zero-copy reads
> ---------------
>
>                 Key: CASSANDRA-1714
>                 URL: https://issues.apache.org/jira/browse/CASSANDRA-1714
>             Project: Cassandra
>          Issue Type: Improvement
>          Components: Core
>            Reporter: Jonathan Ellis
>            Assignee: Pavel Yaskevich
>             Fix For: 0.7.1
>
>         Attachments: CASSANDRA-1714.patch, zerocopy.txt
>
>   Original Estimate: 32h
>  Remaining Estimate: 32h
>
> Since we are already using mmap'd ByteBuffers in MappedFileDataInput we should be able to do zero-copy reads (via buffer.slice()), which would give us better performance than CASSANDRA-1651 without having to worry about buffer management.

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