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

Jon Masamitsu jon.masamitsu at oracle.com
Tue Nov 17 21:12:05 UTC 2015



On 11/17/2015 12:00 PM, Kim Barrett wrote:
> 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
> ------------------------------------------------------------------------------
> 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.

It's actually an afterthought.

I've moved it here.

http://cr.openjdk.java.net/~jmasa/8133023/webrev.01/

Jon


>
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>



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