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From "Jonathan Ellis (JIRA)" <>
Subject [jira] [Commented] (CASSANDRA-6746) Reads have a slow ramp up in speed
Date Thu, 13 Mar 2014 04:27:45 GMT


Jonathan Ellis commented on CASSANDRA-6746:

bq. if true we do not explicitly DONTNEED, but we do not WILLNEED either

I get that, but the reason this was introduced in the first place was because the default
behavior of (at least some) Linux kernels was to evict other data in favor of the newly flushed.

> Reads have a slow ramp up in speed
> ----------------------------------
>                 Key: CASSANDRA-6746
>                 URL:
>             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, 6746-patched.png, 6746.txt, cassandra-2.0-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|]

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