JDK-8292082 : Deprecate UseRTM* for removal
  • Type: Enhancement
  • Component: hotspot
  • Sub-Component: compiler
  • Affected Version: 20
  • Priority: P4
  • Status: Closed
  • Resolution: Won't Fix
  • OS: generic
  • CPU: x86,ppc,x86_64
  • Submitted: 2022-08-09
  • Updated: 2024-03-25
  • Resolved: 2022-10-05
Related Reports
CSR :  
Relates :  
Description
HotSpot supports RTM (restricted transactional memory) to be used for locking and deoptimization. RTM has since been disabled in Intel processors due to security vulnerabilities [0] and IBM removed support for it since its Power 10 line. RTM adds unnecessarily to complexity and maintenance burden.

I would like to propose to deprecate the relevant flags for removal, and actually remove the flags and all related code in a later release, unless somebody comes up with a good reason and performance comparison to show that it's worth keeping.

[0] https://en.wikipedia.org/wiki/Transactional_Synchronization_Extensions#History_and_bugs

Comments
We determined in the PR that we'll keep RTM locking for the time being.
05-10-2022

A pull request was submitted for review. URL: https://git.openjdk.org/jdk/pull/9810 Date: 2022-08-09 15:59:21 +0000
09-08-2022