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  1. JDK
  2. JDK-6191063

Improve startup of server VM

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    Details

    • Type: Enhancement
    • Status: Resolved
    • Priority: P3
    • Resolution: Fixed
    • Affects Version/s: 6
    • Fix Version/s: 6
    • Component/s: hotspot
    • Labels:
      None
    • Subcomponent:
    • Resolved In Build:
      b14
    • CPU:
      sparc
    • OS:
      solaris_9

      Description

      After the talk with Hui about his investigation of startup time
      I spent few days to look on VM with server compiler startup.
      I used jdk 1.5.0_01.b02.

      The main difference came when I set -XX:CompilationPolicyChoice=0
      which use simple compilation policy (compile only hot methods and OSR
      and don't compile caller methods). The default for C2 is
      -XX:CompilationPolicyChoice=1 when we try to compile a caller method
      which called a hot method.

      Client (C1) compiler has CompilationPolicyChoice=0.

      Alacrity run confirmed my results:

      http://alacrity.sfbay/query/enes.jsp?VersionSelector_baseline=1.5.0%7Ckvn_c2start_bas_174842&VersionSelector=1.5.0%7Ckvn_c2start_cp0_185821&esum=Summary&pval=0.01&type_baseline=o&type_build=o


      And here are my manual runs of refWorkload, I ran startup3 andreference_server benchmarks. Full results are in the Comments section.

      Here are startup3 improvements Choice=0 vs Choice=1:
      18.09% PC P3 win2K 1x0.9GHz 512Mb
      12.55% PC P4 win2K 1x1.7GHz 768Mb
      16.56% "epiphone" amd64 linux 1x1.8GHz 1Gb
       5.29% "perf-v6" p4 linux 4x3.2GHz 4Gb (2 cpus + HT)
       8.77% SB2500 US3i Sol9 2x1.2GHz 1Gb
       9.21% SB2500 -d64 US3i Sol9 2x1.2GHz 1Gb

      The only problem with server benchmarks was jetstream
      on x86 (see full results below):
      ========================================================================
      PC P4 win3k 1x1.7GHz
      choice=1 jetstream 10 38.01 2.45
      ----
      choice=0 jetstream 10 36.82 3.18 -3.22 0.363
      ========================================================================
      PC P3 win2K 1x0.9GHz
      choice=1 jetstream 10 27.68 0.23
      ----
      choice=0 jetstream 10 24.19 0.26 -14.41 0.000
      ========================================================================
      But on amd64 1x1.8GHz it is opposite:
      choice=1 jetstream 10 117.21 4.20
      ----
      choice=0 jetstream 10 130.75 6.63 11.55 0.000
      ========================================================================

      I found the cause of the regression in jetstream on Windows.

      The jetstream use the "-r 5" option to run 5 times in one VM
      and we take the last run (5th) result as result of the benchmark.
      The problem is that we can still compile at this time.
      With -XX:CompilationPolicyChoice=0 we delay some compilations
      and such happens that we have heavy compilation during the last run:

      ******** Starting run #4 ********
       61 java.nio.ByteBuffer::array (35 bytes)
      Read Text: 125
      Write Text: 422
      Parse Text: 157
      Copy Files: 172
      ******** Starting run #5 ********
       62 java.io.Win32FileSystem::isSlash (18 bytes)
       63 java.io.Win32FileSystem::normalize (231 bytes)
      Read Text: 203
      Write Text: 421
      Parse Text: 156
      Copy Files: 156

      And on the machine with one cpu the compilation time added to the
      final result. We lose even when we have better "Overall Score":

      Run's score 52.17:
      ******** Starting run #5 ********
      Read Text: 125
      Write Text: 438
      Parse Text: 157
      Copy Files: 157
      Overall Score: 8656

      Run's score 46.64:
      ******** Starting run #5 ********
      Read Text: 203
      Write Text: 422
      Parse Text: 157
      Copy Files: 157
      Overall Score: 8641
      ###@###.### 11/4/04 23:22 GMT

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            Assignee:
            kvn Vladimir Kozlov
            Reporter:
            kvn Vladimir Kozlov
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