topic Re: doubt about swapinfo. in Operating System - HP-UX

doubt about swapinfo.

kumasudh — Tue, 30 Mar 2010 10:09:06 GMT

Hello Gurus,

I have a question regarding the swapinfo. I have the following output from my HPUX system.

Mb Mb Mb PCT START/ Mb
TYPE AVAIL USED FREE USED LIMIT RESERVE PRI NAME
dev 2048 0 2048 0% 0 - 1 /dev/vg00/lvol2
reserve - 2021 -2021
memory 2858 2051 807 72%
total 4906 4072 834 83% - 0 -

If you see the output, there was no page-in/page-out activity (dev/PCT used column is 0%), But still some of my process are failing to start. Going by the ouput, we could see that the total VM is still available. Could you please confirm this swapinfo output is not indicating any abnormal situation ?

Best Regards
Sudhir

Re: question on swapinfo.

Dennis Handly — Sun, 18 Sep 2011 22:10:13 GMT

>Going by the output, we could see that the total VM is still available.

You only have 834 Mb available. Almost all of your device swap is reserved, only 27 Mb free.

If you want to start more processes, you need more swap or RAM.

Re: doubt about swapinfo.

kumasudh — Tue, 30 Mar 2010 10:36:58 GMT

Hi Denis,

Thanks a lot for your reply.
>>You only have 834 Mb available. Almost all of your device swap is reserved, only 27 Mb free.

My question is how the psuedo swap space usage is increasing while i dont see any swapping happening on this machine. What is the min. VM (swap space + psuedo space) requirement for a process to get started ?

Best Regards
Sudhir

Re: doubt about swapinfo.

Michal Kapalka (mikap) — Tue, 30 Mar 2010 10:55:38 GMT

hi,

check this thread from ITRC :

http://forums11.itrc.hp.com/service/forums/questionanswer.do?threadId=1281526

i think good explanation about the pseudo-swap.

mikap

Re: question on swapinfo.

Dennis Handly — Sun, 18 Sep 2011 22:10:54 GMT

>My question is how the pseudo swap space usage is increasing while I don't see any swapping happening on this machine.

The simple way to analyze it is to not look at anything other than the total line.

>What is the min VM (swap space + pseudo space) requirement for a process to get started?

Again, don't look at details. The minimum swap is whatever the process requested. That's composed of the size of initial data, the size of the stack, the size of any mmap private regions, any increase in heap area. New shared memory segments.