Request for Review (s) - 8133023: ParallelGCThreads is not calculated correctly

Kim Barrett kim.barrett at oracle.com
Tue Nov 17 20:00:13 UTC 2015


On Nov 12, 2015, at 4:31 PM, Jon Masamitsu <jon.masamitsu at oracle.com> wrote:
> 
> GC calls VM_Version::calc_parallel_worker_threads() to determine
> the number of GC threads to create.  On Sparc it checks for newer
> Niagara hardware to decide the proper scaling of the GC threads with
> the hardware threads.  calc_parallel_worker_threads() was being called
> before enough information was gathered to determine the Sparc hardware.
> 
> Moved the gathering of information needed to earlier in the JVM
> initialization.
> 
> http://cr.openjdk.java.net/~jmasa/8133023/webrev.00/
> 
> https://bugs.openjdk.java.net/browse/JDK-8133023

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src/cpu/sparc/vm/vm_version_sparc.hpp
 155   static bool is_niagara_plus()         { assert(_features != 0, "System initialization is not complete."); return is_T_family(_features) && !is_T1_model(_features); }

I agree with Thomas, _features should be compared with unknown_m
rather than 0 in the assert.

But that assert seems oddly placed and lonely.  If that _feature check
has an assert, why don't all the others?  To me that assert seems like
leftover development/debug code at this point.

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