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Posted to commits@cassandra.apache.org by "ZhaoYang (Jira)" <ji...@apache.org> on 2020/08/13 04:23:00 UTC
[jira] [Comment Edited] (CASSANDRA-16036) Add flag to disable chunk
cache and disable by default
[ https://issues.apache.org/jira/browse/CASSANDRA-16036?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=17176756#comment-17176756 ]
ZhaoYang edited comment on CASSANDRA-16036 at 8/13/20, 4:22 AM:
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[~dcapwell] sorry, won't be able to look deeper into chunk cache this week. But based on the comparison between 3.0 baseline, 4.0 chunk cache, and 4.0 no chunk cache, disabling chunk-cache didn't bridge the gap between 3.0 and 4.0. I wonder if something else is affecting the perf instead of chunk cache. do you have JFR?
was (Author: jasonstack):
[~dcapwell] sorry, won't be able to look deeper into chunk cache this week. But based on the comparison between 3.0 baseline, 4.0 chunk cache, and 4.0 no chunk cache, disabling chunk-cache didn't bridge the gap between 3.0 and 4.0. I wonder if something else is affecting the perf instead of chunk cache. do you have
> Add flag to disable chunk cache and disable by default
> ------------------------------------------------------
>
> Key: CASSANDRA-16036
> URL: https://issues.apache.org/jira/browse/CASSANDRA-16036
> Project: Cassandra
> Issue Type: Bug
> Components: Legacy/Local Write-Read Paths
> Reporter: David Capwell
> Assignee: David Capwell
> Priority: Normal
> Fix For: 4.0-beta
>
> Attachments: clustering-in-clause_latency_selects_baseline.png, clustering-in-clause_latency_under90_selects_baseline.png, clustering-slice_latency_selects_baseline.png, clustering-slice_latency_under90_selects_baseline.png, medium-blobs_latency_selects_baseline.png, medium-blobs_latency_under90_selects_baseline.png, partition-single-row-read_latency_selects_baseline.png, partition-single-row-read_latency_under90_selects_baseline.png
>
>
> 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.
> {code}
> 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]
> {code}
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