Choice of C compiler doesn't matter much for Java...

Article: Nehalem Performance Preview
By: Henrik S (henrik.stahl.delete@this.nospam.oracle.nothanks.com), April 12, 2009 6:37 am
Room: Moderated Discussions
Paul (no@thanks.com) on 4/12/09 wrote:
---------------------------
>Henrik S (henrik.stahl@nospam.oracle.nothanks.com) on 4/12/09 wrote:
>---------------------------
>>No difference between Windows 2003 and 2008. We get slightly higher scores (1%?)
>>on Windows than Linux, something we believe can be partially attributed to a gcc
>>compiler optimization we don't use on Linux (omit_frame_pointer), but we haven't
>>analyzed it lately so it may be something else (if any Linux gurus here feel like
>>figuring that one out, I'd be happy to help them get started).
>
>I think that omit-frame-pointer pointer has been part of -O for GCC for a while,
>a lot of work was put in to make debugging possible on x86 without the frame pointer.

Only on 64-bit (as someone else pointed out here). OTOH, we always use the 64-bit JVM for SPECjbb2005 since it is faster.

>The other thing it would be interesting to do is to compile your codebase with
>the Intel C++ compiler, you can get evaluation versions of this and if your code
>compiles with both GCC and MSVC++ then you ought to be able to get it past Intel C++ without much effort.

I believe one reason we use gcc is because it is better at cross-compiling (we also use gcc for Solaris/SPARC and Linux/Itanium).

>A 1% difference might not even be the compiler it could be some difference in CPU
>affinity, or slighly non optimal case in the VM or something.

Yes. It's a theory and it actually goes against my previous claim that no significant time is spent in code compiled by gcc anyway. Which probably makes it wrong, now that I think of it...

>Recent versions of VTune have a library you can link your code to which allows
>you to teach VTune about JIT compiled code, it could be instructive to try that as well.

Heh. We use VTune extensively and worked with Intel to ensure that the JIT compiled code support worked back when we were the only JVM vendor to care much about Intel hardware (Sun was in bed with AMD, and IBM seemed to focus on other things).

The problem with this ~1% deficiency is that it is not high priority to resolve - it's really minimal, won't affect any customers and not visible on other important workloads (such as SPECjAppServer2004). We just never seem to get down to doing it...

Henrik
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Nehalem review upDavid Kanter2009/04/07 02:43 AM
  Nehalem review upnoone2009/04/07 05:48 AM
  Strange jbb on HarpertownHenrik S2009/04/07 07:29 AM
    Strange jbb on HarpertownDavid Kanter2009/04/07 10:19 AM
      Strange jbb on HarpertownHenrik S2009/04/07 08:33 PM
        Strange jbb on HarpertownChris2009/04/07 11:54 PM
          Strange jbb on HarpertownHenrik S2009/04/08 01:40 AM
  Nehalem review upVincent Diepeveen2009/04/07 07:34 AM
    Nehalem review upJack2009/04/09 03:51 PM
      Nehalem review upVincent Diepeveen2009/04/10 12:58 AM
        Nehalem review upMichael S2009/04/10 02:45 AM
          Nehalem review upEduardoS2009/04/10 06:01 AM
            Nehalem review upMichael S2009/04/10 06:56 AM
          Nehalem review upEugene Nalimov2009/04/10 08:12 AM
          Choice of C compiler doesn't matter much for Java...Henrik S2009/04/10 09:10 AM
            Choice of C compiler doesn't matter much for Java...EduardoS2009/04/10 01:49 PM
              Choice of C compiler doesn't matter much for Java...Henrik S2009/04/11 06:13 AM
                Choice of C compiler doesn't matter much for Java...EduardoS2009/04/11 10:30 AM
                  Large pagesDavid Kanter2009/04/11 01:02 PM
                  Choice of C compiler doesn't matter much for Java...Henrik S2009/04/11 10:06 PM
                    Choice of C compiler doesn't matter much for Java...Paul2009/04/12 12:53 AM
                      Choice of C compiler doesn't matter much for Java...iz2009/04/12 01:59 AM
                      Choice of C compiler doesn't matter much for Java...Henrik S2009/04/12 06:37 AM
                    Choice of C compiler doesn't matter much for Java...EduardoS2009/04/12 07:08 AM
                      Choice of C compiler doesn't matter much for Java...Henrik S2009/04/12 08:25 AM
                        Choice of C compiler doesn't matter much for Java...EduardoS2009/04/12 04:24 PM
                          Choice of C compiler doesn't matter much for Java...Henrik S2009/04/12 09:18 PM
                            Thread costsDavid Kanter2009/04/12 11:12 PM
                              Thread costsHenrik S2009/04/14 01:08 PM
            Choice of C compiler doesn't matter much for Java...Michael S2009/04/11 07:53 AM
              Choice of C compiler doesn't matter much for Java...Henrik S2009/04/11 10:08 PM
          Nehalem review upVincent Diepeveen2009/04/11 03:50 PM
            Nehalem review upMichael S2009/04/11 04:12 PM
              Nehalem review upVincent Diepeveen2009/04/12 02:01 AM
                Nehalem review upMichael S2009/04/12 04:07 AM
  Nehalem review uprwessel2009/04/07 01:01 PM
    Nehalem review upslacker2009/04/08 08:11 AM
      Energy vs. powerDavid Kanter2009/04/08 09:11 AM
        Energy vs. powerVincent Diepeveen2009/04/10 01:08 AM
          Energy vs. powerslacker2009/04/10 08:26 AM
            Energy vs. powerRagingDragon2009/04/10 09:19 AM
              Energy vs. powerDavid Kanter2009/04/10 10:47 AM
              Energy vs. powerJack2009/04/10 03:44 PM
                Energy vs. powerslacker2009/04/10 06:00 PM
                  Energy vs. powerJack2009/04/10 06:31 PM
                  Energy vs. powerDavid Kanter2009/04/10 11:16 PM
      Nehalem review uprwessel2009/04/08 01:32 PM
  Minor font issuegpriatko2009/04/07 03:35 PM
    Minor HTML issueDavid Kanter2009/04/07 08:38 PM
      Minor HTML issueDavid Kanter2009/04/07 08:39 PM
  Good work, i look forward to linux and SP2 numbers (NT)PiedPiper2009/04/08 12:52 AM
  Nehalem review upJoe Chang2009/04/10 02:59 AM
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