Problem with RAM size on HP-UX 10.20 B

[Satya_6]

Hi,

We have a HP-UX 10.20 B workstation with 144 MB of main memory installed.

Now the 'top' as well as 'SAM'
show a real memory of 10 MB or less than that always.

And any compilation or linking comes out saying 'Out of Memory"

My question is why the 'top' shows only 10 MB of real memory when there is 144 MB of memory installed? I think the problem of 'Out of memory' is also because of the same reason

Any help would be highly appreciated.

TIA
satya

[Ravi_8]

Hi,

#swapinfo -t

how much is the available memory

[Steve Steel]

Hi


look at /var/adm/syslog/syslog.log

find the memory information logged


Jun 5 10:32:18 xantia vmunix:
Jun 5 10:32:18 xantia vmunix: Memory Information:
Jun 5 10:32:18 xantia vmunix: physical page size = 4096 bytes, logical page
size = 4096 bytes
Jun 5 10:32:18 xantia vmunix: Physical: 65536 Kbytes, lockable: 42504 Kbyte
s, available: 51444 Kbytes

Also what is the value os swapmem_on and dbc_max_pct in your kernel.

Show swapinfo -at


Steve Steel

[T G Manikandan]

Top command does not infact show the amount of total memory on the system.

To find the memory info you can use

#echo physmem/D | adb /stand/vmunix /dev/kmem
multiply the output by 4096 to get the info in bytes.

The out of memory error is due to

1.Probably the system is running out of memory.you can check that using
swapinfo -ta

2.check your kernel parameters

maxdsiz
maxssiz
maxtsiz and their 64 equ.

How much memory you have on the system?

[Bill Hassell · Accepted solution]

144 MB is very, very small so it is not surpring that you would see this message. The good news is trhat you can add a lot of swap space and this problem may disappear. Use the swapon command to additional swap while the system is running.

I said 'may disappear' because the out of memory issue may relate to the kernel fence: maxdsiz It is set tpo 67megs by default so any program that want to grow larger than that will be 'out of memory' even if there are thousands of megs of freespace. I would look at a minimum of 512Mb for your system if you want reasonable performance. Swapping is 100x slower than real memory.

[Satya_6]

Hi

Thanks for the quick reply guys. Looks like the maxdsiz is the problem. It is set to 67 Mb.

swapmem_on is set to 1 and
dbc_max_pct is 50

Can I just go and increase the maxdsiz value?

TIA
satya

[Bill Hassell]

Since you have so little memory, I would suggest setting the DBC max percent to 10 rather than 50, and reduce DBC min percent to 5, Then change maxdsiz to 500 or so. Since this is just an artificial fence to prevent runaway programs from using all of RAM (and swap), there is no side effect from making it larger.

[Satya_6]

Hi,

Thank you very much guys,
Increasing the maxdsiz did the trick. Now it looks it is working fine.

thanks again
satya

[doug hosking]

Yes, maxdsiz often causes this problem. In
newer HP-UX releases the default value has been raised to reduce the frequency of such
problems. Even though you fixed the immediate problem, I would still strongly encourage you to follow Bill's advice about reducing dbc_max_pct from 50 to 10 and setting dbc_min_pct to 5. Your system, which has very limited memory compared with most 10.20 systems, will likely perform better for you, especially when running large programs like compilers.