topic Re: kernel-hugemem in Operating System - Linux

kernel-hugemem

Bob Manocchia — Thu, 12 Feb 2009 18:47:00 GMT

I installed the hugemem kernel on a Red Hat 4 server with 10 gb of memory. I then selected this kernel to boot from and it looks ok but the user says that they still cannot address more than 2gb of memory in their Java app. Is there something else I need to do perhaps a kernel parm need to be tweaked.

Thanks

Re: kernel-hugemem

Steven E. Protter — Thu, 12 Feb 2009 21:24:06 GMT

Shalom,

hugemen kernel permits 16 gb of memory to be addressed via memory management.

The limitation may be in the java app or the tools you are using to compile it.

Please provide more details to get more accurate assistance.

SEP

Re: kernel-hugemem

skt_skt — Fri, 13 Feb 2009 02:02:31 GMT

what about the kernel paramter "kernel.shmmax"? Not sure if that playing a a role in your context.

Re: kernel-hugemem

dirk dierickx — Fri, 13 Feb 2009 07:42:38 GMT

i think the java vm also has an option to set maximum addressable memory, though not sure. might be something to lookup.

Re: kernel-hugemem

Matti_Kurkela — Fri, 13 Feb 2009 15:35:46 GMT

2 GB sounds like the maximum size of a single process in a 32-bit Linux environment.
Running a 32-bit system with 10 GB of memory will allow you to run several processes of 2 GB size in parallel, but it won't allow you to exceed the architectural limitations on per-process address space.

Upgrade to a 64-bit version of the OS and use the -d64 option when starting the Java application.

MK

Re: kernel-hugemem

Bob Manocchia — Fri, 13 Feb 2009 15:38:36 GMT

The developer found that it was a configuration option in his script. Thanks for the help.