JDK-8157560 : Reserve space for allocation prefetch only in builds that support allocation prefetching
  • Type: Bug
  • Component: hotspot
  • Sub-Component: compiler
  • Affected Version: 8u112,9
  • Priority: P2
  • Status: Resolved
  • Resolution: Fixed
  • Submitted: 2016-05-23
  • Updated: 2016-11-23
  • Resolved: 2016-05-24
The Version table provides details related to the release that this issue/RFE will be addressed.

Unresolved : Release in which this issue/RFE will be addressed.
Resolved: Release in which this issue/RFE has been resolved.
Fixed : Release in which this issue/RFE has been fixed. The release containing this fix may be available for download as an Early Access Release or a General Availability Release.

To download the current JDK release, click here.
JDK 9
9 b122Fixed
Related Reports
Relates :  
JDK-8153340 - Disallow misconfiguration and improve the consistency of allocation prefetching
Description
Every thread-local allocation buffer (TLAB) contains a reserved area to accommodate allocation prefetches (i.e., to make sure that instructions performing allocation prefetch do not cause faults). The reserved area is at the end of the TLAB.

Currently, all the reserved area is created in all builds, even though only the C2 compiler generates allocation prefetches. As a result, in builds without C2, some heap space is wasted at the end of each TLAB. Creating the reserved area also causes problems for internal testing of the AllocatePrefetchLines/AllocateInstancePrefetchLines command-line flags.