swapinfo memory size (11.11)

[Vick10]

Hi experts,

Have a question regarding variation in memory size shown by different command in HPUX

I have a server (11.11) with 3072MB RAM, below are the physical memory values displayed by various command. Why does swapinfo shows 2.3MB ??



/root # print_manifest |grep -i memory
Main Memory: 3072 MB
root:
/root # swapinfo
Kb Kb Kb PCT START/ Kb
TYPE AVAIL USED FREE USED LIMIT RESERVE PRI NAME
dev 4194304 107392 4086912 3% 0 - 1 /dev/vg00/lvol2
dev 2097152 107156 1989996 5% 0 - 1 /dev/vg01/lvol1
reserve - 1007836 -1007836
memory 2325480 869836 1455644 37%
root:
/root # dmesg |grep -i physical
physical page size = 4096 bytes, logical page size = 4096 bytes
Physical: 3145728 Kbytes, lockable: 2321100 Kbytes, available: 2679568 Kbytes

[Fabio Ettore · Accepted solution]

Hi Vick,

this is a typical misunderstanding of swapinfo entries. That line called "memory" is not for the amount of physical memory on the system but it's the pseudo-swap. More info from man of swapinfo:

memory
Memory paging area (also known as pseudo-swap). This is the amount of system memory that can be used to hold pages in the event that all of the above paging areas are used up. See "Paging Allocation" below. This line appears only if memory paging is enabled.

HTH.

Best regards,
Fabio

[Steven E. Protter]

Shalom,

If you use swapinfo -tam

You might get the picture of memory use that you need.

It is possible that swapinfo suffers from a bug or incorrect command line parameters.

SEP

[sreekanthtm]

Hi,

Swapinfo is not a good/ recomended cmmand to check the physical memory. you can use print_manifest or cstm

Rgds
Sreekanth

[Don Morris_1]

First, it doesn't. That output is in Kb (not bytes), so the pseudo-swap line is about 2.3Gb. Second -- as others have pointed out -- pseudo-swap is not physical memory.. it is a kernel accounting/reservation pool sized heuristically as some fraction of physical memory (usually between 75 to 87.5%, but really up to the kernel). man 1M swapinfo for more of a description.. no need to write it all again here.

[Vick10]

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