[CASSANDRA-7938] Releases prior to 2.0 gratuitously invalidate buffer cache

• Type: Bug
• Status: Resolved
• Priority: Low
• Resolution: Won't Fix
• Fix Version/s: 1.2.19
• Severity: Low
• Assignee: Unassigned
• Reporter: Matt Stump

Reviewers

Matt Stump

• Created: 15/Sep/14 18:15
• Updated: 16/Apr/19 09:31
• Resolved: 18/Sep/14 17:09

Description

RandomAccessReader gratuitously invalidates the buffer cache in releases prior to 2.0.

Additionally, Linux 3.X kernels spend 30% of CPU time in book keeping for the invalidated pages as captured by CPU flame graphs.

fadvise DONT_NEED should never be called for files other than the commit log segments.

https://github.com/apache/cassandra/blob/cassandra-2.1/src/java/org/apache/cassandra/io/util/RandomAccessReader.java#L168