JDK-8228505 : G1 adds old gen region rs lengths to _young_rs_length
  • Type: Bug
  • Component: hotspot
  • Sub-Component: gc
  • Affected Version: 14
  • Priority: P3
  • Status: Resolved
  • Resolution: Duplicate
  • Submitted: 2019-07-23
  • Updated: 2019-07-26
  • Resolved: 2019-07-26
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JDK 14
14Resolved
Related Reports
Duplicate :  
JDK-8227739 - Merge cost predictions for scanning cards and log buffer entries
Relates :  
JDK-8228504 - Rename max_rs_length to young_rs_length
Relates :  
JDK-8228506 - Remove rs_length_diff related code
Description
The max_rs_length value and related predictor are used to predict total young gen remembered set length.

During the Free CSet phase we add not only young gen regions to the local total that is later assigned to max_rs_length, but also old gen region remembered set sizes.

Fortunately G1 does not (correctly) use this resulting value to update predictions. It is just wasted effort.

Fix this.
Comments
This change has to go with JDK-8227739 because otherwise we would temporarily need both total (young and old) and young gen only remembered set entry sums.
26-07-2019