Description of all flags used in Fujitsu Siemens Primergy RX220 submission with BEA Jrockit® 5.0 

further information on http://edocs.bea.com/jrockit/jrdocs/refman/intro.html



-Xms 
Sets the initial size of the heap. This value can be specified in kilobytes (K,k), megabytes (M,m), or 
gigabytes (G,g).
The default value depends upon the JVM mode: 
-server mode: The default value is the lesser of 25% of the free physical memory or 64 MB. 
-client mode: The default value is the lesser of 25% of the free physical memory or 16 MB. 

-Xmx 
Sets the maximum size of the heap. This value can be specified in kilobytes (K,k), megabytes (M,m), or 
gigabytes (G,g). 
The default value is the lesser of 75% of the total physical memory or 1 GB

-XXaggressive 
Performs adaptive optimizations as early as possible in the Java application run. To do this, 
the bottleneck detector will run with a higher frequency from the start and then gradually lower its frequency. 
This options also tells BEA JRockit to use the available memory aggressively.  

-XXthroughputCompaction
This option adjusts the compaction ratio dynamically based on the ratio of live data in the heap. This option 
is experimental, and has shown improved application throughput for applications with a high allocation rate but 
low ratio of live data.

-XXlazyUnlocking
With this option, locks will not be released when a critical section is exited. Instead, once a lock is acquired, 
the next thread which tries to acquire such a lock will have to check if the lock is/can be released, 
by checking if the initial thread still uses the lock.
A shared lock will convert to a normal lock and not stay in lazy mode.
This option is intended for applications with many unshared locks but can introduce performance penalties 
with application that have many short lived but shared locks.

-XXcompressedRefs
This flag turns on compressed references, which means that all pointers stored on heap are 32-bits. 
This uses less resources of the java heap and transports less data on the memory buss, which both are good 
for performance. 
The heap size will be limited to be less than 4G, so this option can only be used for applications that demand 
less than 4 GB of live data.
The heap will be reduced to meet this size demand if a larger ms or mx is specified.

-XXoptthreads
This option specifies how many optimization threads the JVM will use for the background work of optimizing methods. 
By default one thread is used for this work.

-XXtlaSize 
Sets the thread-local area size. To increase performance JRockit uses thread-local areas for allocation 
of small objects. This option can be used to tune the size of the thread-local areas, which may affect performance. 
The default value is 2KB.