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From "Jonathan Ellis (JIRA)" <j...@apache.org>
Subject [jira] [Comment Edited] (CASSANDRA-6746) Reads have a slow ramp up in speed
Date Fri, 28 Feb 2014 16:50:20 GMT

    [ https://issues.apache.org/jira/browse/CASSANDRA-6746?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=13915966#comment-13915966
] 

Jonathan Ellis edited comment on CASSANDRA-6746 at 2/28/14 4:48 PM:
--------------------------------------------------------------------

bq. On compaction we DONTNEED the replacement sstable.

-No, we don't-

You're right, this is also governed by populate_io_cache_on_flush.  Now I wonder if that's
deliberate or an oversight.


was (Author: jbellis):
bq. On compaction we DONTNEED the replacement sstable.

No, we don't.

> 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, cassandra-2.0-bdplab-trial-fincore.tar.bz2,
cassandra-2.1-bdplab-trial-fincore.tar.bz2
>
>
> 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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