topic Re: lockable memory on the server in Operating System - HP-UX

lockable memory on the server

T G Manikandan — Sun, 31 Mar 2002 11:25:43 GMT

Hello,
I have a L2000 server with 2GB memory.
Physical: 2097152 Kbytes, lockable: 1165112
Kbytes, available: 1360512 Kbytes
The lockable bytes on the server is very less.How can I increase the value.The parameter unlockable_mem on the server is 0.
Please,suggestions!

Re: lockable memory on the server

Wilfred Chau_1 — Sun, 31 Mar 2002 13:35:29 GMT

You can set it up to your physical memory.

http://docs.hp.com//hpux/onlinedocs/os/KCparam.UnlockableMem.html

Re: lockable memory on the server

Sanjay_6 — Sun, 31 Mar 2002 19:49:09 GMT

Hi TG,

Try these couple of links,

http://us-support3.external.hp.com/cki/bin/doc.pl/sid=a4200ad90379d5938a/screen=ckiDisplayDocument?docId=200000042264046

http://us-support3.external.hp.com/cki/bin/doc.pl/sid=a4200ad90379d5938a/screen=ckiDisplayDocument?docId=200000050018417

http://us-support3.external.hp.com/cki/bin/doc.pl/sid=a4200ad90379d5938a/screen=ckiDisplayDocument?docId=200000059988538

Hope this helps.

Regds

Re: lockable memory on the server

Bill Hassell — Mon, 01 Apr 2002 15:57:15 GMT

Without making any special changes to the kernel parameters, the lockable memory is what is leftover after the operatings system grabs it's portion. So if you have very large kernel parameters for nfile, nproc, ninode, etc, then the kernel will need many megs of RAM for it's tables and processes.

There are a lot more questions to ask about memory usage...lockable RAM is a small corener case of most memory problems. Make sure your buffer cache is not using 50% of your RAM and get a copy of psram from:

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

Thois will show all processes sorted by the amount of RAM used. An example of psram is attached.

Re: lockable memory on the server

T G Manikandan — Thu, 04 Apr 2002 08:01:17 GMT

Hello,
Thanks for the replies.

I have attached the kmtune ouput.Please check which all values I should reduce and some brief on that.

Thanks

Re: lockable memory on the server

T G Manikandan — Fri, 05 Apr 2002 07:13:31 GMT

Hello,
How can I increase the number of lockable bytes on the server?
The total memory is 2GB and the lockable bytes is 1.1GB.

Thanks

Re: lockable memory on the server

Trevor Dyson — Fri, 05 Apr 2002 14:29:52 GMT

Hi,
The way I understand things to work is that your lockable memory is set to roughly 75% of available memory. Available memory is what is left over after the kernel grabs space for itself and structures determined by the tunable parameter values.

With a physical memory size of 2097152 Kbytes, and available memory size of 1360512 Kbytes this means to me that the kernel is using up 736640 Kbytes (roughly 736 Megabytes). Thats huge!.

Looking at the tunable parameters I can see that semaphore related parameters (sem*) are the ones that are most above the default values, notably:
Parameter:semmni
Value: 7500
Default:64 Parameter:semmns Value:7500
Default:128
Parameter:semmnu Value:7500 Default:30
Parameter:semume
Value:7500 Default:10

I do not know for sure that these are the cause of such a large kernel but I would investigate why these need to be so high. The setting for these parameters would be determined by the application/RDBMS requirements so I would check the app/DB documentation and recomendations for these parameters.

Another parameter worth some investigation is maxvgs. The default is 10 and yours is set to 100. If you do not have close to 100 volume groups then you should really reduce this down but I can not see this using up hundreds of megabytes of RAM.

Re: lockable memory on the server

T G Manikandan — Mon, 08 Apr 2002 02:22:11 GMT

Hello,
Thanks for the replies.Some more input please

Thanks