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https://issues.apache.org/jira/browse/CASSANDRA-7040?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=13969514#comment-13969514
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Benedict commented on CASSANDRA-7040:
-------------------------------------
Further, once we have this, we can experiment with periodically locking access
to the disks (for short, say 20-50ms periods) in order to let
compactions/flushes catch up with any outstanding work, if they appear to be
getting behind.
> Replace read/write stage with per-disk access coordination
> ----------------------------------------------------------
>
> Key: CASSANDRA-7040
> URL: https://issues.apache.org/jira/browse/CASSANDRA-7040
> Project: Cassandra
> Issue Type: Improvement
> Components: Core
> Reporter: Benedict
> Labels: performance
> Fix For: 3.0
>
>
> As discussed in CASSANDRA-6995, current coordination of access to disk is
> suboptimal: instead of ensuring disk accesses alone are coordinated, we
> instead coordinate at the level of operations that may touch the disks,
> ensuring only so many are proceeding at once. As such, tuning is difficult,
> and we incur unnecessary delays for operations that would not touch the
> disk(s).
> Ideally we would instead simply use a shared coordination primitive to gate
> access to the disk when we perform a rebuffer. This work would dovetail very
> nicely with any work in CASSANDRA-5863, as we could prevent any blocking or
> context switching for data that we know to be cached. It also, as far as I
> can tell, obviates the need for CASSANDRA-5239.
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