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

memory allocation

svilen888 — Wed, 05 May 2004 07:17:53 GMT

Our DBA intend to increase SGA to 1 GB.
Please help me to analyze how mach is system memory of the mashine and how it is distributed:
There are some outputs of the commands:

#top

.....
Memory: 2053468K (1739836K) real, 2558200K (2070888K) virtual, 3580748K free Pa
ge# 1/61
...........

#swapinfo -d
TYPE AVAIL USED FREE USED
dev 2097152 0 2097152 0%

#vmstat -n
VM
memory page
avm free re at pi po
512264 895550 16 4 0 0

thanks for help.

Re: memory allocation

svilen888 — Wed, 05 May 2004 07:21:39 GMT

And also:
#swapinfo -t

Kb Kb Kb PCT
TYPE AVAIL USED FREE USED
dev 2097152 0 2097152 0% 0 - 1 /dev/vg00/lvol2
reserve - 2097152 -2097152
memory 6558268 2356364 4201904 36%
total 8655420 4453516 4201904 51%

Re: memory allocation

RAC_1 — Wed, 05 May 2004 07:28:01 GMT

Do you have glance installed? top is not really not good at checking memory details.

Also there are tools as kmeminfo and shminfo to report detailed memory usages for kernel memory and shrared memory.

Anil

Re: memory allocation

Joseph Loo — Wed, 05 May 2004 07:28:13 GMT

hi,

could you do this

# dmesg|grep Physical

where the first series of number after "Physical:" is your physical memory. if your DBA wants to set SGA to 1GB, try to set kernel parameter, shmmax to at least more than 1GB.

from the vmstat info, the free column which is in pages (1 page about 4kb) if converted to GB is the number of free memory in bytes.

regards

Re: memory allocation

Pete Randall — Wed, 05 May 2004 07:29:51 GMT

What I'm seeing is a system that's in very good shape as far as memory is concerned. This is indicated by the fact that you've used no device swap - you're not swapping at all. You're using approximately 34% of your memory, both for reserved pages and actual running programs.

To see how much physical RAM you have, run this little script:

HPUX=/stand/vmunix
MAJORREV=$(uname -r | cut -f2 -d .)
if [ $MAJORREV -ge "11.0" ]
then
MYSYMBOL="phys_mem_pages"
else
MYSYMBOL="physmem"
fi

MYMEM=$(echo "${MYSYMBOL}/D" \
| adb $HPUX /dev/kmem \
| grep "${MYSYMBOL}: *." \
| awk '{printf "%.0f MB\n",$2/256}')
echo $MYMEM

Pete

Re: memory allocation

svilen888 — Wed, 05 May 2004 07:54:10 GMT

Physical Memory: 8183.3 MB

Real Memory:
Active: 1862097.9 KB
Total: 2063139.9 KB

Virtual Memory:
Active: 2267487.3 KB
Total: 2553303.3 KB

Free Memory Pages: 893382 at 4 KB/page

Swap Space:
Avail: 2048 MB
Used: 2048 MB

Why I have so big difference between Phisical memory and Real memory?
Does it mean that I cannot addressing
the rest Phisical memory?

Re: memory allocation

svilen888 — Wed, 05 May 2004 07:56:30 GMT

Sorry, points coming soon :))
And the last message is my final question :))

Re: memory allocation

Roberto Polli — Wed, 05 May 2004 08:42:48 GMT

Your physical memory is given from

vmstat -P

don't care other outputs (PS. where did you get the 'REAL memory'?)

Peace, R.

Re: memory allocation

Sanjay_6 — Wed, 05 May 2004 08:46:44 GMT

Hi,

Try this link for explanations,

http://www1.itrc.hp.com/service/cki/docDisplay.do?docLocale=en_US&docId=200000068500228

The itrc doc id is A3940339.

Hope this helps.

Regds

Re: memory allocation

Bharat Katkar — Wed, 05 May 2004 08:59:43 GMT

What i understand from your output is:
1. You have 6 GB RAM (Physical Memory)
2. 2 GB device swap configured on lvol2

8 GB is addition of this two.

And in top what you see in Memory Data is:
Includes virtual and real memory in use (with the amount of
memory considered "active" in parentheses) and the amount of
free memory.

See man top for more info.