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Why I got a very high physical memory utilization?

 
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qiuhzcs-air.com
Occasional Visitor

Why I got a very high physical memory utilization?

Hi all
I have a performance problem on a rx8640, the server has 24 Processors and 96GB physical memory, running oracle 10g with HP-UX 11.31.

Now the problem is: the physical memory utilization upto 85%, but the processors utilization always less then 10%.

kmeinfo output:
Physical memory = 25098979 95.7g 100%
Free memory = 3270192 12.5g 13%
User processes = 0 0.0 0% details with -user
System = 236 944.0k 0%
Kernel = 0 0.0 0% kernel text and data
Dynamic Arenas = 1927254 7.4g 8% details with -arena
BTREE_NODE_OLA_ = 453234 1.7g 2%
vx_inode_kmcach = 218688 854.2m 1%
vx_global_kmcac = 169982 664.0m 1%
reg_fixed_arena = 166878 651.9m 1%
btree_chunk_are = 140658 549.4m 1%
Other arenas = 777814 3.0g 3% details with -arena
Super page pool = 19608 76.6m 0% details with -kas
Static Tables = 1384939 5.3g 6% details with -static
pfdat = 1225536 4.7g 5%
vhpt = 131072 512.0m 1%
text = 8475 33.1m 0% vmunix text section
inode = 7616 29.8m 0%
bss = 5144 20.1m 0% vmunix bss section
Other tables = 7095 27.7m 0% details with -static
Buffer cache = 118 472.0k 0% details with -bufcache
UFC meta mrg = 118 472.0k 0%
UFC file mrg = 11929303 45.5g 48%

Now, focus on the "UFC file mrg", it used over 45GB memory. What's it meaning and use for? Could somebody guide me how to fix the problem.
Thans a lot.

Qiu Hongzhou


9 REPLIES
Stephan.
Honored Contributor
Solution

Re: Why I got a very high physical memory utilization?

Hi,
UFC = Unified File Cache
Default value is 50% of system memory

It will be controled using kctune:
filecache_max
filecache_min



Michal Kapalka (mikap)
Honored Contributor

Re: Why I got a very high physical memory utilization?

hi,

if you are using Oracle or SAP, or other product that is memory consuming.

its normal.

ask the DBA to check the DB setting and recomended kernel parameter.

check some advices from metalink on oracle.

mikap
Stephan.
Honored Contributor

Re: Why I got a very high physical memory utilization?

Michal Kapalka (mikap)
Honored Contributor

Re: Why I got a very high physical memory utilization?

hi,

check the memmory utilization with glance or gpm (gui).

mikap
SUDHAKAR_18
Trusted Contributor

Re: Why I got a very high physical memory utilization?

Hi,

Pls go through this for more info on UFC.

h20338.www2.hp.com/hpux11i/downloads/Unifiedfilecache.pdf

Normally Itanium server shows high memory utilisation .Dynamic Arena/Super Page Pool are using High Memory Resources as the system is having free physical memory available. It automatically shrinks down if the application or user process require more memory for a process.

This is normal behavior.
Bill Hassell
Honored Contributor

Re: Why I got a very high physical memory utilization?

Memory and CPU usage are unrelated. It is easy to write a 64 bit program that allocates all free memory (such as the UFC file mrg) and then consume no CPU time. If you start filling up the file system cache by running find / and du -s /, then you'll see CPU time climb as directories are scanned and placed into the cache. Run the same commands again and they will complete very quickly (with high CPU usage) because most of the details are in memory and disk I/O is not needed.

There is no problem. The UFC cache manager uses what is available but will shrink back usage when other processes need memory.


Bill Hassell, sysadmin
Shailendran V Naidu
Frequent Advisor

Re: Why I got a very high physical memory utilization?

Hi
thats common in all servers that are running databases (Oracle/SAP)

I have seen servers at 95% Physical memory utilization.

having said that you may want to observe the swap space utilization too. Because after the memory fills up the server will start paging.

Thats when you will have issues from application team about perfomance.

So run
# swapinfo -tam

If the swap space is also showing high utilization.. You will need to run a back ground check - like if there is any process that is participating in memory leaks. Or take a look at the history of the server if it had any performance issue in the past.
If the server is memory intensive then - Add memory and increase swap space.

Most likely you should be OK.
qiuhzcs-air.com
Occasional Visitor

Re: Why I got a very high physical memory utilization?

Hi all:

So,it seems not to be a problem immediately, and I will keep my eyes on the SWAP utilization.

Thanks for all your responses.
Steven E. Protter
Exalted Contributor

Re: Why I got a very high physical memory utilization?

Shalom,

There is no relationship between CPU utilization and memory utilization. The questions phrasing seems to indicate you are surprised to be out of memory due to low CPU usage.

Look for leaker's:
http://www.hpux.ws/?p=8

Memory leaks are often the cause of this condition, and are caused by improper coding and inadequate quality assurance of software in the development phase.

SEP
Steven E Protter
Owner of ISN Corporation
http://isnamerica.com
http://hpuxconsulting.com
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