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https://issues.apache.org/jira/browse/CASSANDRA-1470?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel
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Pavel Yaskevich updated CASSANDRA-1470:
---------------------------------------
Attachment: CASSANDRA-1470-v13-0.7.patch
CommitLog/SSTableWriter uses BRAF with posix_fadvice(DONTNEED) for writes.
Test using -S 2048 on writes
byte[] | Direct I/O + posix_fadvice on commitlog/sstable writes (this shows
elapsed_time)
-----------------------------
write | 34 | 34
-----------------------------
read | 92 | 88
-----------------------------
read | 38 | 63
-----------------------------
write | 36 | 35
-----------------------------
read | 108 | 57
-----------------------------
Looks like fadvice is solution is working...
> use direct io for compaction
> ----------------------------
>
> Key: CASSANDRA-1470
> URL: https://issues.apache.org/jira/browse/CASSANDRA-1470
> Project: Cassandra
> Issue Type: Improvement
> Components: Core
> Reporter: Jonathan Ellis
> Assignee: Pavel Yaskevich
> Fix For: 0.7.1
>
> Attachments: 1470-v2.txt, 1470.txt, CASSANDRA-1470-for-0.6.patch,
> CASSANDRA-1470-v10-for-0.7.patch, CASSANDRA-1470-v11-for-0.7.patch,
> CASSANDRA-1470-v12-0.7.patch, CASSANDRA-1470-v13-0.7.patch,
> CASSANDRA-1470-v2.patch,
> CASSANDRA-1470-v3-0.7-with-LastErrorException-support.patch,
> CASSANDRA-1470-v4-for-0.7.patch, CASSANDRA-1470-v5-for-0.7.patch,
> CASSANDRA-1470-v6-for-0.7.patch, CASSANDRA-1470-v7-for-0.7.patch,
> CASSANDRA-1470-v8-for-0.7.patch, CASSANDRA-1470-v9-for-0.7.patch,
> CASSANDRA-1470.patch,
> use.DirectIORandomAccessFile.for.commitlog.against.1022235.patch
>
>
> When compaction scans through a group of sstables, it forces the data in the
> os buffer cache being used for hot reads, which can have a dramatic negative
> effect on performance.
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