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swapinfo

himacs
Super Advisor

swapinfo


Hi Admins,

Please find my swapinfo -atm output

uxgsmc@UAEDXBPDCBDBP01 /tmp>kctune swapmem_on
Tunable Value Expression
swapmem_on 0 0
uxgsmc@UAEDXBPDCBDBP01 /tmp>swapinfo -atm
Mb Mb Mb PCT START/ Mb
TYPE AVAIL USED FREE USED LIMIT RESERVE PRI NAME
dev 12288 572 11716 5% 0 - 1 /dev/vg00/lvol2
dev 4096 572 3524 14% 0 - 1 /dev/vg00/lvol10
reserve - 12273 -12273
total 16384 13417 2967 82% - 0 -


Primary swap usage is 5%
Secondery swap usage is 14%

But reserved is more

How to resolve this..Please suggest

Regards
himacs



3 REPLIES
Dennis Handly
Acclaimed Contributor

Re: swapinfo

>swapmem_on 0 0

The first thing you should do is to turn pseudo-swap on. (Requires a reboot.)

>How to resolve this?

What's to resolve? Everything is fine. You have reserved more swap that is actually currently being used.
You can run processes that use only 2.9 Gb more.
Michal Kapalka (mikap)
Honored Contributor

Re: swapinfo

hi,

there is no problem.

mikap
R.K. #
Honored Contributor

Re: swapinfo

Hello Himacs,

Brief description on swapinfo o/p:
DEV LINE(S):
- are the actual physical swap device(s)
- show if swapping has actually occurred. The PCT USED column in the dev lines represents the value last attained during a previous period of swapping.

RESERVE LINE : indicate how much of the swap device(s) has(have) been set aside for memory should it need to be swapped.
So, as said already, 'reserve' is ok.

MEMORY LINE: indicative of how much of pseudo-swap has been reserved. When present, indicates pseudo-swap is enabled (i.e. swapmem_on kernel paraemter is set to 1, which is the default.)


WHEN pseudo swap is required:-

HP-UX reserves swap space for a process when it is created, to ensure that a running process never needs to be killed due to insufficient swap. This was difficult, however, for systems needing gigabytes of swap space with gigabytes of physical memory. This tunable was created to allow system swap space to be less than core memory. To accomplish this, a portion of physical memory is set aside as 'pseudo-swap' space. While actual swap space is still available, processes still reserve all the swap they will need at fork or execute time from the physical device or file system swap. Once this swap is completely used, new processes do not reserve swap, and each page which would have been swapped to the physical device or file system is instead locked in memory and counted as part of the pseudo-swap space.

In other words, if there is no device or file system swap available, the system allocates pseudo-swap as a last resort.
Don't fix what ain't broke