MWA metric GBL_MEM_ACTIVE_VIRT_UTIL

[Angelito_1]

Hi,

Why is this happening?:

When GBL_MEM_ACTIVE_VIRT_UTIL decreases, GBL_SWAP_SPACE_UTIL increases.

GBL_MEM_ACTIVE_VIRT_UTIL:
The percentage of total virtual memory active at the end of the interval. Active virtual memory is the virtual memory associated with processes that are currently on the run queue or processes that have executed recently. This is the sum of the virtual memory sizes of the data and stack regions for these processes.

GBL_SWAP_SPACE_UTIL:
The percent of swap space available that was reserved by running processes in the interval.

Thanks in advance.

[Emil Velez]

Active virtual memory is the memory that has been recently accessed. This memory is paged in or kept into physical memory. A page which has not recently been accessed is eligable to be paged (swapped) to swap space pagea. When a system fills up physical memory it must start paging out virtual pages that have not recently been used. So if you do not access pages recently and you are under memory pressure (physical memory is full) then vhand moves pages that have not been recently accessed to swap space to make room for pages that need to be accessed.

Good luck I hope this makes sense.

Emil

[Raj D.]

Angelito,

As per the glance metrics details you are right. Can you paste us the output pls.

Cheers,
Raj.

[Raj D.]

Angelito ,

GBL_MEM_ACTIVE_BIRT_UTIL,
Active virtual memory is the virtual memory associated with processes that are currently on the run queue or processes that have executed recently.

Pls Note:

GBL_SWAP_SPACE_AVAIL , is the total amount of potential swap space, in MB. On HP-UX, this is the sum of the device swap areas enabled by the swapon command, the allocated size of any file system swap areas, and the allocated size of pseudo swap in memory if enabled. Note that this is potential swap space. This is the same as (AVAIL: total) as reported by the swapinfo -tm command.


So when GBL_MEM_ACTIVE_BIRT_UTIL decreases , that means the active processes for runqueues are decreases, resulting in using more memory to finishup those processes (caused swapinfo -tm to show more usage for virtual memory). Hence GBL_SWAP_SPACE_UTIL shows increasing, while GBL_MEM_ACTIVE_BIRT_UTIL decreases. So it makes sense.


Cheers,
Raj.

[Raj D.]

Angelito,

I have checked the above two metrics and found GBL_SWAP_SPACE_UTIL does not increses significantly with decrease with GBL_MEM_ACTIVE_VIRT_UTIL . Even it found that GBL_SWAP_SPACE_UTIL is remain same.

If you are checking through a script keep an eye on swapinfo -tm on the other window , and it will show the same thing , that will shows the value of GBL_SWAP_SPACE_UTIL equal to the total swap space utilization.


------------------------------------------
Here is the output that I checked on a 11.11 system:


(1) GBL_MEM_ACTIVE_VIRT_UTIL (2) GBL_SWAP_SPACE_UTIL :

tech@root> glance -j 3 -iterations 100 -adviser_only -syntax systab.adv 3

Welcome to GlancePlus


86.15 14.00
86.15 14.00
86.15 14.00
86.15 14.00
86.15 14.00
86.15 14.00
86.15 14.00
75.86 14.00
75.86 14.00
75.86 14.00
75.86 14.00
75.86 14.00
75.86 14.00
77.76 14.00
77.76 14.00
77.76 14.00
77.42 14.00
77.42 14.00
77.42 14.00
77.56 14.00
77.56 14.00
77.56 14.00
77.56 14.00
81.80 14.00
81.80 14.00
81.80 14.00
79.62 14.00
79.62 14.00
79.62 14.00
77.50 14.00
77.50 14.00
77.50 14.00
77.76 14.00
77.76 14.00
77.76 14.00
77.76 14.00
75.64 14.00
75.64 14.00
75.64 14.00




tech@root> cat systab.adv
print GBL_MEM_ACTIVE_VIRT_UTIL|7|2,GBL_SWAP_SPACE_UTIL|7|2
tech@root>

tech@root> swapinfo -tm
Mb Mb Mb PCT START/ Mb
TYPE AVAIL USED FREE USED LIMIT RESERVE PRI NAME
dev 4096 0 4096 0% 0 - 1 /dev/vg00/lvol2
reserve - 213 -213
memory 1184 545 639 46%
total 5280 758 4522 14% - 0 -
tech@root>
---------------------------------------------

Hope this will help,

Cheers,
Raj.