Re: classic JVM vs J9 JVM

Steve,

answers inline
Regards
 
Stefan Tageson


midrange-l-bounces@xxxxxxxxxxxx wrote on 2007-02-23 16:12:34:

what is the advantage to running the new ( V5R4 ) 32 bit J9 JVM on the 

i5?
<stefan> Most noticeably a 40% memory usage reduction as we now are using 
32 bit instead of 64. </stefan>

J9 JVM is PASE resident. Just like PHP.  Which means calling into a
Java method from RPG requires a tags active -> inactive thunk.  That
has to be slow.

<stefan> Not shown when benchmarking the Lawson M3 application. </stefan>
 

The 32 bit J9 JVM has a 4GB memory limit. That is 4GB of memory per
process, but there are processes that run on the system, like
websphere web server, which can use more than 4GB of Java managed
memory.

<stefan> Correct. But you save a large amount of memory. </stefan>

The classic 64 bit JVM, the one iSeries IBM had been touting as the
fastest, most scalable JVM on the market, will not be available after
V5R5?

<stefan> Don't know. But the JIT-compiler i J9 does a better job than 
crtjvapgm in the original 64 bit jvm. </stefan>
 

After V5R5, only PASE Java will be supported?

V5R5 will have a 64 bit version of the J9, PASE resident, JVM. Does
that mean the tags inactive thunk that occurs when calling from ILE
code into PASE will no longer apply, will be mitigated?

-Steve