topic Re: Shared memory in Operating System - HP-UX

Shared memory

Belinda Dermody — Wed, 14 Sep 2005 15:01:21 GMT

I Have a RP5470 running 11i and I just added 2 additonal gig of memory for a total of 4 gig with 2 CPU's. Do I have to do anything with the kernel to increase the shared memory. We added the 2 gig for the Sybase server and the DBA says I have to change a parameter like they do on the Sun box's. I have never heard of this before for HP, but there is a lot of things that I do not know.

Re: Shared memory

Raj D. — Wed, 14 Sep 2005 15:03:44 GMT

Hi James ,

You can add the system swap , to make it 150% of Physical Memroy.

You can check by :
# swapinfo -tm

Cheers,
Raj.

Re: Shared memory

James R. Ferguson — Wed, 14 Sep 2005 15:14:53 GMT

Hi James:

You may want to evaluate some of your current kernel parameters. This document discusses all of them. There is a section devoete to shared memory.

http://docs.hp.com/en/TKP-90202/index.html

You can get a current summary for your server by running:

# kmtune -l

See the 'kmtune' manpages too, for more information.

Regards!

...JRF...

Re: Shared memory

Sandman! — Wed, 14 Sep 2005 16:42:12 GMT

Looks like your DBA is talking about the shared IPC resources that are set in the /etc/system file under Solaris. In HP they are all part of the kernel (some dynamic others not) and you can query their values with the following command:

# kmtune -q semmni
# kmtune -q semmns
# kmtune -q shmmni
# kmtune -q shmseg
# kmtune -q shmmax

cheers!

Re: Shared memory

TwoProc — Wed, 14 Sep 2005 18:06:25 GMT

As the others have posted - it's the shm**** parameters that need to be reviewed in the kernel, in particular for this question - shmmax.

Re: Shared memory

Tim Nelson — Wed, 14 Sep 2005 18:30:01 GMT

Other than making sure you up the swap space if needed ( watch out for maxswapchunks parameter, if not set high enough then no matter how much swapspace you allocate system will only use maxswapchunks)

shmmax 2048000000, 4096000000 etc...