Shared Memory Question

[Filosofo]

Hello,
Can I see the "value" of my shared memory, and I can change it?

Please help.

Filo

[Stefan Farrelly]

/usr/sbin/kmtune | grep shmmax

shows the value of your shared memory. And you can change it by modifying this value in the kernel, then rebooting to make it active. You can use SAM to do it.

[Filosofo]

Thanks Stefan,
My shmmax parameters is:
0x160000000 (5905580032)

and I have 6GB of physical memory.
What are the maximum value that I can assigned to this parameter?

Hello

Filo

[Tore_1]

man shmmax (probably not installed on your system)

shmmax(5) shmmax(5)
Tunable Kernel Parameters



NAME
shmmax - maximum size (in bytes) for a System V shared memory segment

VALUES
Default
0X4000000

Allowed values
Minimum: 2048

Maximum: 0X4000000 for a 32 bit kernel,
and 0x40000000000 for a 64 bit kernel

[Stefan Farrelly]

The max for shmmax is 1Gigabyte on 32bit HP-UX, or 1Terabyte on 64bit HP-UX.

[Giorgio Tassi]

Hello, thanks fo helps,
I can see the virtual memory that the system now utilized?
I try to execute top and I see:
Memory: 6539432K (1973508K) real, 11655124K (5637824K) virtual, 54119436K free Page# 1/1357

and shmmax set to 5905580032 (0x160000000)

Help me please

Filo

[Bill Hassell]

ipcs -bmop will show just the shared memory segments that are allocated. However, when a question like thisa comes up, it usually means that an application (like Oracle) needs more shared memory to improve speed and cannot obtain the required amount.

There have been several posts about this question and the severe limitations imposed on 32bit applications. Simply put, there is a single map for all 32bit applications and it contains memory mapped files, shared libraries and shared memory segments used by other programs. It can get fragmented (due to stop/restart of programs) such that a large single section of RAM is no longer available. The only fix is a reboot, or use memory windows (for 11.0 and 11i, assuming you have lots of RAM like 4Gb or more).

To see the fragmentation, use shminfo from: ftp://hprc.external.hp.com/sysadmin/programs/shminfo/

[Stuart Abramson_2]

bill:

How do I download "shminfo"? This server doesn't seem to take anonymous ftp from MS Internet Explorer.

Stuart

ftp://hprc.external.hp.com/sysadmin/programs/shminfo/

[Zafar A. Mohammed_1]

Try this
ftp://contrib:9unsupp8@hprc.external.hp.com/sysadmin/programs/shminfo/

Thanks
Zafar

[Bill Hassell]

Sorry about the URL....I copied from IExplorer but it looks like a recent patch now automatically suppresses the login information. As you've seen, anonymous FTP does not exist at that site (for security) so you have to specify the login: contrib, and the password: 9unsupp8

Note also that IE 5 and higher has had a very bad bug where folder views cause ftp to hang. Just go into Tools->Internet options->Advanced and turn off folder views for FTP (a waste of screen space anyways):

ftp://contrib:9unsupp8@hprc.external.hp.com/sysadmin/programs/shminfo/