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https://issues.apache.org/jira/browse/CASSANDRA-6746?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=13915949#comment-13915949
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Jonathan Ellis commented on CASSANDRA-6746:
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bq. The result being that we do not "skip IO cache" in 2.0.
Well, we do if JNA is installed -- the difference is that we don't ship JNA out
of the box. :)
bq. if we're compacting live data we will actively destroy the page cache when
the OS listens stringently to the DONTNEED
The behavior on flush and compaction is actually slightly different:
* on flush, we actively DONTNEED unless populate_io_cache_on_flush is enabled
[false by default]
* on compact, we WILLNEED partitions that are "hot" in the key cache, unless
compaction_preheat_key_cache is disabled [true by default]. Nothing is
WONTNEEDed.
We should probably create tables for short tests with
populate_io_cache_on_flush enabled. /cc [~enigmacurry] [~mshuler]
> Reads have a slow ramp up in speed
> ----------------------------------
>
> Key: CASSANDRA-6746
> URL: https://issues.apache.org/jira/browse/CASSANDRA-6746
> Project: Cassandra
> Issue Type: Bug
> Components: Core
> Reporter: Ryan McGuire
> Assignee: Benedict
> Labels: performance
> Fix For: 2.1 beta2
>
> Attachments: 2.1_vs_2.0_read.png
>
>
> On a physical four node cluister I am doing a big write and then a big read.
> The read takes a long time to ramp up to respectable speeds.
> !2.1_vs_2.0_read.png!
> [See data
> here|http://ryanmcguire.info/ds/graph/graph.html?stats=stats.2.1_vs_2.0_vs_1.2.retry1.json&metric=interval_op_rate&operation=stress-read&smoothing=1]
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