topic Re: HP-UX base kernel memory allocation in Operating System - HP-UX

HP-UX base kernel memory allocation

Dario_C — Fri, 30 Jul 2010 09:28:07 GMT

Hello to all,
This may seem a stupid question, but I still can't find a satisfying answer.

I need to know how to estimate the amount of system memory allocated by the HP-UX kernel(11iv2 & 11iv3) at system startup assuming that I have all my kernel tunables at the default value and no applications or databases running on it.

In short, how many of my system memory is in use immediately after boot?

I know that system memory depends mostly on buffer/file caches, inode cache, page size and overheads.

For me it would be helpful to know that, for example, with a system with x cpus and y GB RAM the system memory in use after boot is around z% of the total RAM.

It would be also helpful if some doc exists about this particular argument.

Thank you in advance and regards,

Dario

Re: HP-UX base kernel memory allocation

Steven E. Protter — Fri, 30 Jul 2010 11:51:18 GMT

Shalom,

The only practical way to do this is to use glance. Glance is available for 60 days use without a license and it has the ability to show you exactly what memory the kernel is using.

To estimate changes:

You can however just boot the kernel itself and see memory use.

Boot the system hpux -is single user mode.

Then the kernel is the only thing running besides the shell.

mount /usr
Use your favorite tool to see actual memory use.

With 11.31 most of the kernel is dynamic so you can make changes on the fly and see the results with glance/gpm

SEP

Re: HP-UX base kernel memory allocation

Dario_C — Fri, 30 Jul 2010 12:09:54 GMT

Thanks for the reply.

But what I'm looking for is a more general answer. One that is applicable to any system.

I know that doesn't exist an unique answer. But perhaps an approximation can be estimated in some way.

Re: HP-UX base kernel memory allocation

muruganantham raju — Sat, 31 Jul 2010 06:16:44 GMT

Hi Dario,
kmeminfo in HPUX will get you everthing you are looking for.

# ./kmeminfo
tool: kmeminfo 10.09 - libp4 9.460 - libhpux 1.306
unix: /stand/current/vmunix 11.23 64bit Madison 3-9M on host "amds1"
core: /dev/kmem live
link: Thu Nov 27 03:51:43 IST 2008
boot: Mon Jun 14 18:43:56 2010
time: Sat Jul 31 12:46:32 2010
nbpg: 4096 bytes

----------------------------------------------------------------------
Physical memory usage summary (in page/byte/percent):

Physical memory = 257062 1004.1m 100%
Free memory = 1813 7.1m 1%
User processes = 106014 414.1m 41% details with -user
Detached SHMEM = 1 4.0k 0% details with -shmem
System = 141073 551.1m 55%
Kernel = 111549 435.7m 43% kernel text and data
Dynamic Arenas = 47929 187.2m 19% details with -arena
vx_global_pool = 6996 27.3m 3%
vx_buffer_cache = 5440 21.2m 2%
spinlock = 5103 19.9m 2%
M_TEMP = 3058 11.9m 1%
ALLOCB_MBLK_LM = 2269 8.9m 1%
Other arenas = 25063 97.9m 10% details with -arena
Super page pool = 11423 44.6m 4% details with -kas
Emergency pool = 538 2.1m 0% system critical reserve
UAREA's = 5616 21.9m 2%
Static Tables = 28700 112.1m 11% details with -static
text = 7700 30.1m 3% vmunix text section
nbuf = 6080 23.8m 2% bufcache headers
pfdat = 6024 23.5m 2%
vhpt = 2048 8.0m 1%
bss = 1990 7.8m 1% vmunix bss section
Other tables = 4857 19.0m 2% details with -static
Buffer cache = 29524 115.3m 11% details with -bufcache

You might have to download this tool if not available in your system.

Regards,
Muru

Re: HP-UX base kernel memory allocation

Bill Hassell — Sun, 01 Aug 2010 01:06:07 GMT

The general answer is that "it depends". A base installation of HP-UX for 10.01 or 10.20 is smaller than 11.00 and later. So the answer will be different for each release of the OS. Furthermore, kernel may be tuned differently for different operating environments. Starting with 11i, you can buy HP-UX with pre-installed products and these environments will change kernel memory requirements. But wait, there's more...Itanium boxes will have very different memory usage than PARISC. And at 11.31, the kernel has significant changes to allow dynamic allocation of several internal tables which means that the kernel may use more RAM at different times.

> For me it would be helpful to know that, for example, with a system with x cpus and y GB RAM the system memory in use after boot is around z% of the total RAM.

The number of CPUs will not affect kernel memory. I would be very concerned if kernel memory (which ranges from 250MB to 2000MB, versions 10.20,11.00,11.11,11.23,11.31 both PA and IA) usage is a big factor. For very small systems (1GB RAM or less), the kernel will be a large percentage (25% to 75% but you would never put a significant application like database or web server on such tiny systems. Performance will be horrible for these tiny systems. A minimum for any HP-UX system would be 4GB and for Oracle or Sybase, 8GB-12GB for simple (but fast) systems, 24GB-64GB for big systems. With these numbers, kernel memory usage will be 2%-10%. But when you plan for RAM, remember that the buffer (file) cache should be 500-3000MB and shared memory for applications like databases may need 1GB-10GB to meet performance goals.