JDK10/RFR(L): 8172231: SPARC ISA/CPU feature detection is broken/insufficient (on Solaris).

Patric Hedlin patric.hedlin at oracle.com
Fri Apr 28 13:48:49 UTC 2017

Dear all,

I would like to ask for help to review the following change/update:

Issue: https://bugs.openjdk.java.net/browse/JDK-8172231

Webrev: http://cr.openjdk.java.net/~neliasso/8172231/

8172231: SPARC ISA/CPU feature detection is broken/insufficient (on 

     Updating SPARC feature/capability detection (incorporating changes 
from Martin Walsh).
     More complete set of features as provided by 'getisax(2)' 
interface, propagated via JVMCI.
     More robust hardware probing for additional features (up to Core S4).
     Removing support for old, pre Niagara, hardware.
     Removing support for old, pre 11.1, Solaris.

     Changed behaviour:
     Changing SPARC setup for AllocatePrefetchLines and 
     such that they will (still) be doubled when cache-line size is 
small (32 bytes),
     but more moderately increased on new/contemporary hardware (inc >= 
     Changing to default instruction fetch alignment based on derived 
caps. instead
     of relying on default/configuration values.

     The above changes also subsumes:
     8035146: assert(is_T_family(features) == is_niagara(features), 
"Niagara should be T series") is incorrect
     8054979: Remove unnecessary defines in SPARC's 


     Current hardware detection on Solaris/SPARC is not up to date with 
the "latest" (here,
     meaning commercially available server solutions, i.e. T7/M7). To 
facilitate improved
     use of the new hardware features provided (by Core S3&S4) these 
capabilities need to
     be recognised by the JVM.

     NOTE: This update is limited to Core S3&S4, i.e. not including Core 
S5. Proper Core S5
     support will be added when regular testing and benchmarking 
resources are available,
     i.e. regular testing need to include M8 hardware.


     This update will introduce some redundancies into the code base, 
features and definitions
     currently not used, as well as a (small) number of FIXMEs, 
addressed by subsequent bug or
     feature updates/patches. Fujitsu HW is treated very conservatively.


     Mostly tested on JDK9 (RBT/hotspot/comp). Only local testing on 
JDK10 (jtreg/hotspot).


     Benchmark reports from a limited set of runs can be found at:




     (Limited availability of M7 hardware prevents complete suites/runs.)

Best regards,

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