[jira] [Commented] (CASSANDRA-6746) Reads have a slow ramp up in speed

["Benedict (JIRA)" <ji...@apache.org>]

    [ https://issues.apache.org/jira/browse/CASSANDRA-6746?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=13977235#comment-13977235 ] 

Benedict commented on CASSANDRA-6746:
-------------------------------------

I've updated the ticket to a minor improvement and moved it to no-release for now, as CASSANDRA-6916 looks to solve the regression; not sure if you still want to investigate the read-ahead changes you were looking at still though as an improvement, [~xedin]? If not I'll resolve the ticket.

> Reads have a slow ramp up in speed
> ----------------------------------
>
>                 Key: CASSANDRA-6746
>                 URL: https://issues.apache.org/jira/browse/CASSANDRA-6746
>             Project: Cassandra
>          Issue Type: Improvement
>          Components: Core
>            Reporter: Ryan McGuire
>            Assignee: Benedict
>            Priority: Minor
>              Labels: performance
>         Attachments: 2.1_vs_2.0_read.png, 6746-buffered-io-tweaks.png, 6746-patched.png, 6746.blockdev_setra.full.png, 6746.blockdev_setra.zoomed.png, 6746.buffered_io_tweaks.logs.tar.gz, 6746.buffered_io_tweaks.write-flush-compact-mixed.png, 6746.buffered_io_tweaks.write-read-flush-compact.png, 6746.txt, buffered-io-tweaks.patch, 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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