There is performance regression in b54 on x86 (32-bits VM on multi-cpus Opteron)
after Coleen's putback 0050919182406.coleenp.pt.rme.ws.
The test is provided by Dough Lea. I attached it.

You have to use the flag -XX:ProfileMaturityPercentage=0 to workaround
the bug 6329104.

prt-solamd64-q1-4% psrinfo -v
Status of virtual processor 0 as of: 10/04/2005 10:33:51
  on-line since 09/14/2005 20:52:20.
  The i386 processor operates at 2589 MHz,
        and has an i387 compatible floating point processor.
Status of virtual processor 1 as of: 10/04/2005 10:33:51
  on-line since 09/14/2005 20:52:23.
  The i386 processor operates at 2589 MHz,
        and has an i387 compatible floating point processor.

prt-solamd64-q1-4% uname -a
SunOS prt-solamd64-q1-4 5.10 Generic i86pc i386 i86pc

prt-solamd64-q1-4% /tmp/kvn/jdk1.6.0/bin/java -version
java version "1.6.0-ea"
Java(TM) 2 Runtime Environment, Standard Edition (build 1.6.0-ea-b12)
Java HotSpot(TM) Server VM (build 20050916202013.coleenp.rt_merge, mixed mode)
prt-solamd64-q1-4% time /tmp/kvn/jdk1.6.0/bin/java -XX:ProfileMaturityPercentage=0 CollectionLoops RWCollection
Class: RWCollection threads: 2 size: 10000 ins: 100 rem: 1 ops: 100000
Threads: 1 : 18847 ns per op 1.884758981s run time
Threads: 1 : 18745 ns per op 1.874591785s run time
Threads: 1 : 19904 ns per op 1.990489363s run time
Threads: 1 : 18669 ns per op 1.866918584s run time
Threads: 2 : 19770 ns per op 3.954020314s run time
Threads: 2 : 19783 ns per op 3.956649671s run time
16.0u 1.0s 0:16 104% 0+0k 0+0io 0pf+0w

prt-solamd64-q1-4% /tmp/kvn/jdk1.6.0/bin/java -version
java version "1.6.0-ea"
Java(TM) 2 Runtime Environment, Standard Edition (build 1.6.0-ea-b12)
Java HotSpot(TM) Server VM (build 20050919182406.coleenp.pt.rme.ws, mixed mode)
prt-solamd64-q1-4% time /tmp/kvn/jdk1.6.0/bin/java -XX:ProfileMaturityPercentage=0 CollectionLoops RWCollection
Class: RWCollection threads: 2 size: 10000 ins: 100 rem: 1 ops: 100000
Threads: 1 : 31216 ns per op 3.121675978s run time
Threads: 1 : 32242 ns per op 3.224239121s run time
Threads: 1 : 32717 ns per op 3.271775494s run time
Threads: 1 : 31701 ns per op 3.170120089s run time
Threads: 2 : 35219 ns per op 7.043972725s run time
Threads: 2 : 34752 ns per op 6.950433048s run time
27.0u 1.0s 0:27 101% 0+0k 0+0io 0pf+0w