[CASSANDRA-16036] Add flag to disable chunk cache and disable by default

• Type: Bug
• Status: Resolved
• Priority: Normal
• Resolution: Fixed
• Fix Version/s: 4.0-beta3, 4.0
• Component/s: Legacy/Local Write-Read Paths
• Bug Category: Degradation - Performance Bug/Regression
• Severity: Normal
• Complexity: Low Hanging Fruit
• Discovered By: Performance Regression Test
• Platform: All
• Since Version: 3.11.0

Source Control Link

https://github.com/apache/cassandra/commit/d4f501892d882cb1bf62529f0e72cf7d9c61e323

Test and Documentation Plan

CI and performance tests

• Assignee: David Capwell
• Reporter: David Capwell

Authors

David Capwell

Reviewers

Jon Meredith, Zhao Yang

• Created: 07/Aug/20 05:12
• Updated: 03/Jan/21 17:02
• Resolved: 30/Sep/20 00:08

Description

Chunk cache is enabled by default and doesn’t have a flag to disable without impacting networking. In performance testing 4.0 against 3.0 I found that reads were slower in 4.0 and after profiling found that the ChunkCache was partially to blame; after disabling the chunk cache, read performance had improved.

40_w_cc-selects.hdr
#[Mean    =     11.50063, StdDeviation   =     13.44014]
#[Max     =    482.41254, Total count    =       316477]
#[Buckets =           25, SubBuckets     =       262144]

40_wo_cc-selects.hdr
#[Mean    =      9.82115, StdDeviation   =     10.14270]
#[Max     =    522.36493, Total count    =       317444]
#[Buckets =           25, SubBuckets     =       262144]

Issue Links

• is related to: CASSANDRA-15229 Segregate Network and Chunk Cache BufferPools and Recirculate Partially Freed Chunks
• relates to: CASSANDRA-16078 Performance regression for queries accessing multiple rows
• relates to: CASSANDRA-16158 Avoid Unnecessary Chunk Cache Usage During Compaction
• links to: Circle CI: trunk
• links to: GitHub Branch: trunk