topic Re: memory not continous in Operating System - HP-UX

memory not continous

j773303 — Tue, 02 Jan 2007 03:11:02 GMT

He Expert,
I've a question about memory alloaction problem. When run a applicaion, it failed to starting may be due to no continue memory. The free memory is enough to run the AP, but AP need a continuous memory to allocate.

Is there any solution to let memory to be continue without reboot machine ?

Thanks,

Re: memory not continous

Peter Godron — Tue, 02 Jan 2007 04:46:27 GMT

Hi,
each process is allocated a certain amount of memory it can use.
See ulimit -a

Why don't you allocate the amount of memory you need for the AP at the start of the program (i.e. use an array)

Re: memory not continous

j773303 — Tue, 02 Jan 2007 05:20:45 GMT

Hi,
Due to the AP vendor said that the memory not cotinue, so the program not starting correctly. But this is not sure the root cause. I just want to know, is it possible re-orginize memory to be contigue in HPUX ?

Thanks,

Re: memory not continous

Peter Godron — Tue, 02 Jan 2007 05:37:33 GMT

Hi,
the concept of contiguous memory is not really true, please see Bills answer in:
http://forums1.itrc.hp.com/service/forums/questionanswer.do?threadId=1054587

This referred thread is another example of why people should always complete threads detailing the solution. Would have been helpful for this case.

Re: memory not continous

Jaime Bolanos Rojas. — Tue, 02 Jan 2007 07:56:51 GMT

j773303,

Remember that shared memory can not bypass quadrants of memory in the system, there for either the company that created the Appl never study hp-ux architecture or you need to defragment your memory.

Regards,

Jaime.

Re: memory not continous

Bill Hassell — Tue, 02 Jan 2007 08:40:33 GMT

Your vendor has not been very clear. Is the application failing to obtain local memory or shared memory? I will take a guess that it is shared memory and indeed there are issues with regard to 32bit applications and large amounts of shared memory. If root terminates programs with kill -9 (a terrible technique) then shared memory fragmentation is very common. The fix is to remove all unused shared memory segments, but if you do not know exactly which segments are unused, removing these segments will crash various programs.

32bit programs have severe limitations for memory management, one of them being that a single shared memory map is used for all 32bit applications. So as applications are stopped and started, this map can become fragmented. The only way to prevent this is to use memory windows so each application has it's own memory map. This assumes that you are running on a supported version of HP-UX.

Re: memory not continous

Jaime Bolanos Rojas. — Tue, 02 Jan 2007 08:47:31 GMT

Bill,

Someday I wish I can be as smart as you, those answers are worth money!

Regards,

Jaime.

Re: memory not continous

Sandman! — Tue, 02 Jan 2007 12:49:43 GMT

Was this application ever able to get and attach the amount of contiguous memory it needs or is it a new application that has been recently installed on the machine and this is the first time that you are trying to run it?