topic Re: Increasing the memory in Operating System - HP-UX

Increasing the memory

prakasse — Tue, 18 Sep 2007 03:48:18 GMT

Hi all,

Looks like our rx2620(11.23) system only has 388MB real memory assigned, but the physical memory is 4G.

How do I increase the real memory on this system?

top shows the following information:
System: hprx2620 Mon Sep 17 11:28:00 2007
Load averages: 0.00, 0.00, 0.00
157 processes: 133 sleeping, 23 running, 1 zombie
Memory: 388264K (277720K) real, 1278248K (1104076K) virtual, 1429056K free Page

vmstat results:
# vmstat
procs memory page
faults cpu
r b w avm free re at pi po fr de sr in
sy cs us sy id
2 0 0 272368 357021 12 4 0 0 0 0 0 424
3827 110 2 0 98

Thanks in advance,
Senthil

Re: Increasing the memory

Dennis Handly — Tue, 18 Sep 2007 04:06:36 GMT

I believe the standard disclaimer is don't expect top to be accurate.
This link may be helpful:
http://forums1.itrc.hp.com/service/forums/questionanswer.do?threadId=1081452

Re: Increasing the memory

Steven E. Protter — Tue, 18 Sep 2007 04:27:46 GMT

Shalom,

swapinfo -tam

Most common issue is the default buffer cache setting.

dbc_max_pct defaults to 50, which means 50% or a whole big pile of memory. Sometimes it helps performance, sometimes not.

I generally reduce it to between 5-10. You can use kctune to do it on the fly or sam kernel configuration configurable parameters.

SEP

Re: Increasing the memory

Don Morris_1 — Tue, 18 Sep 2007 06:13:40 GMT

In this case, it is probably fairly accurate -- you just have to remember what it reports.

top is reporting in the Memory line the Virtual and Real (physical) consumption by the user space processes it lists. (Not kernel space). So your Real is only a reflection of the actual RAM consumption of what you're running right now. To answer your literal question, to increase the Real memory reported -- run more programs that consume actual RAM pages.

You get some idea of the system with Real (User used) plus Free (truly free memory) -- but it is misleading since the big missing piece there is Kernel/System. (In your case, it looks like about 2.5Gb). Since the kernel has several caches for various purposes (on 11.23, as others have stated the buffer cache is a major one) -- it can be holding memory away from the completely Free state but where it can quickly/easily reclaim it if the need arises. So 2Gb (50%) may be in your dynamic buffer cache... shrinkable if needed. (I'd be willing to be that .5Gb or a bit more is probably legitimately consumed by the kernel and isn't easily reclaimed).

If you really want to know the memory conditions of the system, you always want to use Glance instead of top.

Re: Increasing the memory

Victor Fridyev — Tue, 18 Sep 2007 06:31:13 GMT

In order to see RAM sizefor Itanium , use the following command:
echo phys_mem_pages/jd |adb /stand/vmunix /dev/kmem |
awk 'NR>1 { print $1/1024, "MB"}'

HTH