Hi, we have a Dual Opteron with 4GB memory and 4GB swap space and I've tested Suns JDK1.5beta for X86-64 and also the JDK 1.4 from blackdown for X84-64. Blackdown-1.4.2-rc1 Sun 64-Bit Server VM (build 1.5.0-beta-b32c, mixed mode) With my small test program that just allocates memory I was able to allocate as much memory as the system has. About 6-7 GB (RAM and swap space). The system will be slow down when there is no more swap space. But I have also a productive java program that fails with OutOfMemory exception when using the above mentioned JVMs. That program is used in production on a HP/UX server with a HP 64bit JVM with about 3GB memory. When I use the 64bit VMs on linux this program stops much earlier than when using the 32bit VM from Sun. Although I specify -Xmx3000m with the 64 bit VM the program stops writing a system.out with free heap memory of more than 2GB. I tried to increase the stack size but that gave me the same result than before. Is there any limit on the number of objects the garbage collector can handle? My feeling is that there is still a variable in the VM that is not correctly ported to 64bit. Richard, where can I get the IBM VM for AMD64 for these tests? oli <quote who="Richard Mixon (qwest)">
Have you checked the IBM JRE/JDK 1.4.1 for x86_64 (Opterons)?
I am running IBM JRE/JDK 1.4.1 on a dual Opteron running SuSE SLES 8 for AMD64. When I updated with Service Pack 3, I'm almost sure it said that it was a 64-bit JVM. Whether it will use more than 3.8GB, I do not know yet - I only have 2GB on the server. It would seem awfully strange for a 64-bit program to be limited to 3.8GB of memory.
java version "1.4.1" Java(TM) 2 Runtime Environment, Standard Edition (build 1.4.1) Classic VM (build 1.4.1, J2RE 1.4.1 IBM build cxia32141-20030522 (JIT enabled: jitc)) #:~/tomcat/logs> uname -a Linux kingfish 2.4.21-207-smp #1 SMP Thu Mar 11 15:46:44 UTC 2004 x86_64 unknown #:~/tomcat/logs>
Now, I could see that an HP shop might now want to run the IBM JRE, but that's another issue :)
Hope this helps - Richard
-----Original Message----- From: suseamd64@rgare.com [mailto:suseamd64@rgare.com] Sent: Wednesday, April 14, 2004 2:54 PM To: suse-amd64@suse.com Subject: [suse-amd64] amd64 / linux / java fud?
hello --
i'm sorry if this is not the appropriate place for this question.
an hp loyalist has convinced some decision makers that we can't use opterons for an in house app because he claims there's no linux jvm that uses more than 3.8GB of memory. i couldn't find anything on the blackdown.org site backing this up, and couldn't find anything googling around.
is he just spreading fud? does anyone here have experience and/or documentation that *nix 1.4+ java can use more than 3.8GB of ram?
i just cringe when i see us purchasing super expensive quad itanium-2 boxes when our own in-house testing had our 2-way suse/opteron box out-performing a 4-way itanium(1) machine by 10%+.
again, appologies if this would be better suited on the blackdown.org mailing list.
info appriciated,
-- john
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