RFR (L): 8058354: SPECjvm2008-Derby -2.7% performance regression on Solaris-X64 starting with 9-b29

Thomas Schatzl thomas.schatzl at oracle.com
Thu Mar 26 08:47:40 UTC 2015


Hi Jon,

On Wed, 2015-03-25 at 20:47 -0700, Jon Masamitsu wrote:
> Thomas,
> 
> Haven't gotten very far but let me send you one question.
> 
> http://cr.openjdk.java.net/~tschatzl/8058354/webrev.2_to_3/src/share/vm/gc_implementation/g1/g1PageBasedVirtualSpace.cpp.frames.html
> 
> >   157 void G1PageBasedVirtualSpace::commit_tail() {
> >   158   char* const aligned_end_address = (char*)align_ptr_down(_high_boundary, _page_size);
> >   159   size_t const tail_size = pointer_delta(_high_boundary, aligned_end_address, sizeof(char));
> 
> Should there be a check that tail_size is not 0 before attempting to 
> commit it?

  commit_tail() can only be called if is_last_page_partial() is true,
i.e. tail_size > 0. I can add an assert for that.

Thanks,
  Thomas





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