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  1. JDK
  2. JDK-7041789

30% perf regression with c2/arm following 7017732

    Details

    • Type: Bug
    • Status: Closed
    • Priority: P3
    • Resolution: Fixed
    • Affects Version/s: hs21
    • Fix Version/s: hs21
    • Component/s: hotspot
    • Labels:
      None
    • Subcomponent:
      gc
    • Resolved In Build:
      b14
    • CPU:
      arm
    • OS:
      linux
    • Verification:
      Not verified

      Backports

        Description

        I noticed that I have a perf regression with the current hotspot code on c2/arm compared to measurements I did several weeks ago. So I went back in time and found that on the day I pushed c2/arm to hotspot repos, the perf problem already existed. I pinpointed the change that led to the regression to be:
         
        changeset: 2226:c7f3d0b4570f
        user: never
        date: Fri Mar 18 16:00:34 2011 -0700
        summary: 7017732: move static fields into Class to prepare for perm gen removal
         
        Between this changeset and its parent, best execution time of the javac subtest of specjvm98 goes from ~10 seconds to ~20 seconds. If I run the javac test alone (rather than as the last test of the specjvm98 subtest series), best execution time is ~15 seconds. If I force JavaObjectsInPerm to true, execution time is back to ~10 seconds.
         
        c2 JavaObjectsInPerm=false vs c2 JavaObjectsInPerm=true
         
        ============================================================================
        t
          Benchmark Samples Mean Stdev
          specjvm98 3 56.62 0.03
            compress 3 76.27 0.04
            javac 3 19.16 0.06
            db 3 24.79 0.02
            jack 3 34.64 0.11
            mtrt 3 162.04 0.03
            jess 3 67.20 0.06
            mpegaudio 3 137.23 0.01
        ============================================================================
        t2
          Benchmark Samples Mean Stdev %Diff P Significant
          specjvm98 3 74.95 0.00 32.37 0.002 Yes
            compress 3 80.06 0.00 4.96 0.188 *
            javac 3 35.27 0.02 84.06 0.000 Yes
            db 3 24.70 0.00 -0.39 0.803 *
            jack 3 78.49 0.05 126.57 0.000 Yes
            mtrt 3 177.45 0.01 9.51 0.018 *
            jess 3 99.82 0.01 48.54 0.002 Yes
            mpegaudio 3 137.12 0.00 -0.08 0.884 *
        ============================================================================

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                • Assignee:
                  jmasa Jon Masamitsu (Inactive)
                  Reporter:
                  roland Roland Westrelin
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                  • Created:
                    Updated:
                    Resolved:
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