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high kernel memory usage

yulianto piyut
Valued Contributor

high kernel memory usage


I have server run hp-ux 11.31 that have high kernel memory usage.
# kmeminfo
tool: kmeminfo 9.07 - libp4 9.349 - libhpux 1.241 - HP CONFIDENTIAL
unix: /stand/current/vmunix 11.31 64bit IA64 on host "mrsapdb2"
core: /dev/kmem live
link: Sat Jun 21 14:04:45 SST 2008
boot: Mon Jun 1 22:53:49 2009
time: Thu Jun 11 10:31:24 2009
nbpg: 4096 bytes

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

Physical memory = 4186441 16.0g 100%
Free memory = 373178 1.4g 9%
User processes = 2772798 10.6g 66% details with -user
System = 865819 3.3g 21%
Kernel = 865773 3.3g 21% kernel text and data
Dynamic Arenas = 469713 1.8g 11% details with -arena
btree_chunk_are = 111539 435.7m 3%
vx_global_kmcac = 40276 157.3m 1%
spinlock_arena = 33868 132.3m 1%
FCACHE_ARENA = 24994 97.6m 1%
vx_inode_kmcach = 24096 94.1m 1%
Other arenas = 234940 917.7m 6% details with -arena
Super page pool = 71310 278.6m 2% details with -kas
UAREA's = 9808 38.3m 0%
Static Tables = 263018 1.0g 6% details with -static
pfdat = 204416 798.5m 5%
vhpt = 32768 128.0m 1%
text = 9915 38.7m 0% vmunix text section
inode = 7616 29.8m 0%
bss = 4849 18.9m 0% vmunix bss section
Other tables = 3452 13.5m 0% details with -static
Buffer cache = 46 184.0k 0% details with -bufcache
UFC file mrg = 118373 462.4m 3%
# kctune |grep ninode
ninode 34816 34816
vx_ninode 65000 65000 Immed

how to reduce memory used by kernel ?
Steven E. Protter
Exalted Contributor

Re: high kernel memory usage


If you really want to reduce kernel memory use, you would have to reduce certain parameters.

kctune -l

This is dangerous, because there might be a very good reason where settings are now.

Perhaps take a look at kernel high water marks from Glance/gpm before making any changes. Also check the kernel minimums from your applications. Oracle needs its kernel parameters.

Steven E Protter
Owner of ISN Corporation
Emil Velez
Honored Contributor

Re: high kernel memory usage

run kcweb and look at the graphs that show the useage of kernel paramater tunables before changing any.
yulianto piyut
Valued Contributor

Re: high kernel memory usage

hi emil, output from kcweb:
Tunable Current Usage Current Setting
filecache_max 485322752 489313197
maxdsiz 67108864 1073741824
maxdsiz_64bit 23068672 4294967296
maxfiles_lim 886 4096
maxssiz 786432 134217728
maxssiz_64bit 786432 1073741824
maxtsiz 35864576 100663296
maxtsiz_64bit 318767104 1073741824
maxuprc 54 4096
max_thread_proc 37 1100
msgmni 2 4096
msgtql 0 4096
nflocks 904 4096
ninode 2689 99816
nkthread 610 8416
nproc 262 4200
npty 0 60
nstrpty 8 60
nstrtel 0 60
nswapdev 2 32
nswapfs 0 32
semmni 27 4096
semmns 832 8192
shmmax 9797902336 12884901888
shmmni 12 4096
shmseg 3 512
Respected Contributor

Re: high kernel memory usage

Changing the memory used by the kernel depends of many things, is not that easy to tune it, you would have to make an analisys of what you have installed, what OS are you running, what applications are running, what setting is needed in the kernel tunables for each one of them, etc.
If you start messing around with these, your performance may degrade.

A good starting point is checking the latest installaton guides of your OS and application. Also sometimes latest memory patches could make a difference in how the memory is managed by your system, specially the "vm cumulative patch". Consider installing the latets Quality Patch Bundle.

Jitesh purohit_1
Regular Advisor

Re: high kernel memory usage


The above output of the memory utilization shows as below

1) The physical memory shows as 100% , OUt of which

a) User processes@66%

so its always not necessary your kernel is using more memory .

Are you running any Database/sybase Application on this server .
Laurent Menase
Honored Contributor

Re: high kernel memory usage

add more memory,

It doesn't look reasonable to reduce kernel mem usage there.
dynamic arena reasonably are already at the min 11%
Don Morris_1
Honored Contributor

Re: high kernel memory usage

Free memory is at 9% (1.4Gb). Which means the kernel is still caching aggressively. From the arenas which are on the top of the listing, it looks like file cache metadata -- and the things like btrees will get pruned when the files are closed or there's memory pressure.

Unless you have a definite problem, I wouldn't go changing things.
Venkatesh BL
Honored Contributor

Re: high kernel memory usage

The USER processes are taking up more memory. Look at 'kmeminfo -user all' to get that break down.
Occasional Advisor

Re: high kernel memory usage

fellows i have the same problem here is my situation:
HPUX 11.31 IA64Bit 16Gb Physical Memory
Running Oracle RAC
Sys: 5.9gb User: 8.5gb Free: 878mb
there are page outs at this time, however my fear is if i do not get a good handle on memory usage my system may get into performance issues.
Dennis Handly
Acclaimed Contributor

Re: high kernel memory usage

>Asim: I have the same problem here is my situation:

You should create your own thread so you can assign points. If there is anything useful here, you can provide a link to this thread.
Occasional Advisor

Re: high kernel memory usage