topic Re: Question about swap in Operating System - HP-UX

Question about swap

Subentu — Fri, 26 Dec 2008 07:33:27 GMT

Hi, I have a Rx7620 machine which runs HP-UX 11.23

The memory usage of the system As given by kmeminfo utility is shown bellow:

wbscsp02[/]#/tmp/kmeminfo/kmeminfo
tool: kmeminfo 5.18
unix: /stand/vmunix 11.23 64bit IA64 on "wbscsp02"
core: /dev/kmem live
link: Wed Dec 12 00:38:53 mal 2007
boot: Fri Dec 26 02:31:55 2008
time: Fri Dec 26 12:27:13 2008
nbpg: 4096 bytes

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

Physical memory = 4183868 16.0g 100%
Free memory = 736245 2.8g 18%
User processes = 2170014 8.3g 52% details with -user
System = 1260935 4.8g 30%
Kernel = 633355 2.4g 15% kernel text and data
Dynamic Arenas = 340713 1.3g 8% details with -arena
vx_buffer_cache = 137152 535.8m 3%
M_NFS_GEN = 51672 201.8m 1%
vx_global_pool = 35682 139.4m 1%
vm_pfn2v_arena = 16636 65.0m 0%
spinlock = 16137 63.0m 0%
Other arenas = 83434 325.9m 2% details with -arena
Super page pool = 14531 56.8m 0% details with -kas
Static Tables = 215417 841.5m 5% details with -static
pfdat = 98063 383.1m 2%
nbuf = 60656 236.9m 1% bufcache headers
vhpt = 32768 128.0m 1%
bufhash = 8192 32.0m 0% bufcache hash headers
text = 6402 25.0m 0% vmunix text section
Other tables = 9335 36.5m 0% details with -static
Buffer cache = 627580 2.4g 15% details with -bufcache
wbscsp02[/]#

The swap space details are given bellow:

wbscsp02[/]#swapinfo -at
Kb Kb Kb PCT START/ Kb
TYPE AVAIL USED FREE USED LIMIT RESERVE PRI NAME
dev 4194304 0 4194304 0% 0 - 1 /dev/vg00/lvol2
dev 12288000 0 12288000 0% 0 - 1 /dev/vg00/lvol10
reserve - 10350156 -10350156
total 16482304 10350156 6132148 63% - 0 -
wbscsp02[/]#

swapmem_on parameter is set to 0

My Questions are:
1. What does "reserve" means exactly?
2. From where the reserve space is allocated?
3. Do I need more swap space on my system?

Re: Question about swap

Dennis Handly — Fri, 26 Dec 2008 07:53:59 GMT

>#swapinfo -at

Please provide the -tam output, yours has too many zeros to grok. :-)

>swapmem_on parameter is set to 0

This is broken, immediately set this variable to 1, so you can take advantage of your 16 Gb memory for pseudo-swap.

>1. What does "reserve" means exactly?

It means you have reserved device swap. And in your case, you haven't used it yet.

>2. From where the reserve space is allocated?

Eventually from device swap.

>3. Do I need more swap space on my system?

You have a total of 16 Gb of device swap. And about 12 Gb of pseudo-swap when you enable swapmem_on.

Whether you need more depends on what additional load you'll add to the system. Currently you can only use 6 Gb more (16 swap - 10 reserved).

Re: Question about swap

Subentu — Sat, 27 Dec 2008 10:13:37 GMT

Thanks.

wbscsp02[/]#swapinfo -atm
Mb Mb Mb PCT START/ Mb
TYPE AVAIL USED FREE USED LIMIT RESERVE PRI NAME
dev 4096 0 4096 0% 0 - 1 /dev/vg00/lvol2
dev 12000 0 12000 0% 0 - 1 /dev/vg00/lvol10
reserve - 9747 -9747
total 16096 9747 6349 61% - 0 -

I don't plan on expanding the system. My question is whether I have enough swap for the current set up.

Re: Question about swap

Dennis Handly — Sun, 28 Dec 2008 07:17:14 GMT

>I don't plan on expanding the system.

(I meant expanding the current load, not resources.)

>My question is whether I have enough swap for the current set up?

Was this swapinfo done during your heaviest load? If you haven't gotten any errors about out of swapspace, then you should have enough. Just enable swapmem_on.