Amount of memory in use

The svmon command can provide data on the amount of memory in use.

To print out global statistics, use the -G flag. In the following example, it repeats two times at one-second intervals.

# svmon -G -i 1 2

               size      inuse       free        pin    virtual
memory      1048576     425275     623301      66521     159191
pg space     262144      31995

               work       pers       clnt
pin           46041          0          0
in use       129600     275195          0

PageSize   PoolSize      inuse       pgsp        pin    virtual
s   4 KB          -     404795      31995      46041     159191
L  16 MB          5          0          0          5          0
               size      inuse       free        pin    virtual
memory      1048576     425279     623297      66521     159195
pg space     262144      31995

               work       pers       clnt
pin           46041          0          0
in use       129604     275195          0

PageSize   PoolSize      inuse       pgsp        pin    virtual
s   4 KB          -     404799      31995      46041     159195
L  16 MB          5          0          0          5          0

Notice that if only 4 KB pages are available on the system, the section that breaks down the information per page size is not displayed.

The columns on the resulting svmon report are described as follows:

memory

Statistics describing the use of real memory, shown in 4 KB pages.

size: Total size of memory in 4 KB pages.
inuse: Number of pages in RAM that are in use by a process plus the number of persistent pages that belonged to a terminated process and are still resident in RAM. This value is the total size of memory minus the number of pages on the free list.
free: Number of pages on the free list.
pin: Number of pages pinned in RAM (a pinned page is a page that is always resident in RAM and cannot be paged out).
virtual: Number of pages allocated in the process virtual space.

pg space

Statistics describing the use of paging space, shown in 4 KB pages. The value reported is the actual number of paging-space pages used, which indicates that these pages were paged out to the paging space. This differs from the vmstat command in that the vmstat command's avm column which shows the virtual memory accessed but not necessarily paged out.

size: Total size of paging space in 4 KB pages.
inuse: Total number of allocated pages.

pin

Detailed statistics on the subset of real memory containing pinned pages, shown in 4 KB frames.

work: Number of working pages pinned in RAM.
pers: Number of persistent pages pinned in RAM.
clnt: Number of client pages pinned in RAM.

in use

Detailed statistics on the subset of real memory in use, shown in 4 KB frames.

work: Number of working pages in RAM.
pers: Number of persistent pages in RAM.
clnt: Number of client pages in RAM (client page is a remote file page).

PageSize

Displayed only if page sizes other than 4 KB are available on the system. Specifies individual statistics per page size available on the system.

PageSize: Page size
PoolSize: Number of pages in the reserved memory pool.
inuse: Number of pages used
pgsp: Number of pages allocated in the paging space
pin: Number of pinned pages
virtual: Number of pages allocated in the system virtual space.

In the example, there are 1 048 576 pages of total size of memory. Multiply this number by 4096 to see the total real memory size in bytes (4 GB). While 425 275 pages are in use, there are 623 301 pages on the free list and 66 521 pages are pinned in RAM. Of the total pages in use, there are 129 600 working pages in RAM, 275 195 persistent pages in RAM, and 0 client pages in RAM. The sum of these three parts, plus the memory reserved but not necessarily used by the reserved pools, is equal to the inuse column of the memory part. The pin part divides the pinned memory size into working, persistent, and client categories. The sum of them, plus the memory reserved by the reserved pools, which is always pinned, is equal to the pin column of the memory part. There are 262 144 pages (1 GB) of total paging space, and 31 995 pages are in use. The inuse column of memory is usually greater than the inuse column of pg space because memory for file pages is not freed when a program completes, while paging-space allocation is.