topic Re: question about shared memory in Operating System - HP-UX

question about shared memory

itai weisman — Tue, 12 Jul 2005 10:48:27 GMT

Hello everyone,
on HPUX 11.11 systems on PA-Risc
I'd like to know if there is any way to see if there is a fragmention in the shared memory , in the free area or in the used by any processes , for the shared memory areas that related to 32bit application (1.7gb) and on 64bit application.
I know know how to use 'ipcs' and 'ipcrm' in order to see the segments that are in use, but i don't know how to see the largest contingous free (and used) area in the shared memory.
if anyone has any idea, please let me know.
Thanks people.
Itai

Re: question about shared memory

A. Clay Stephenson — Tue, 12 Jul 2005 12:07:23 GMT

A rather good utility is shminfo. It's an unsupported utility available via ftp from
hprc.external.hp.com. Login as contrib. Password 9unsupp8. Look under sysadmin/programs/shminfo.

Re: question about shared memory

itai weisman — Tue, 12 Jul 2005 12:33:33 GMT

Thanks,
i already checked this proggram - I'm not sure i understood it correctly.
on the last section:

Maximum shmem segment: 1048576 Kbytes (shmmax)
Largest free segment: 1048576 Kbytes (Window id 0 (global) quadrant 2)
Available swap : 3274192 Kbytes (swapspc_cnt)
Available pseudo-swap: 864028 Kbytes (swapmem_cnt)
according to that, my largest free segment is about 1gb, for 32bit application.
but it can't be true, I receive the exact same result, even on machines i'm sure the whole free space should be much smaller (i have a machine that runs Oracle8i 32bit, that uses 1.4 gb out of 1.8 available shared memory for 32bit proggrams, and yet, i receive this result.

Re: question about shared memory

Ermin Borovac — Tue, 12 Jul 2005 23:25:37 GMT

Please run shminfo with -F option. You will show you the largest contiguous free area in the "Global 32-bit shared quadrants" section. I think that largest free segment that you see (1G) is related to use of memory windows.

# shminfo -F
libp4 (7.0): Opening /stand/vmunix /dev/kmem

Loading symbols from /stand/vmunix
shminfo (3.6)

Global 32-bit shared quadrants:
===============================
Space Start End Kbytes Usage
Q4 0x05ef5800.0xc3914000-0xefffffff 727984 FREE

Re: question about shared memory

itai weisman — Wed, 13 Jul 2005 10:59:43 GMT

thanks people, that solved my problem
itai