System Administration Guide: Devices and File Systems

How Do I Know If I Need More Swap Space?

Use the swap -l command to determine if your system needs more swap space.

For example, the following swap -l output shows that this system's swap space is almost entirely consumed or at 100% allocation.

% swap -l
swapfile             dev   swaplo blocks   free
/dev/dsk/c0t0d0s1   136,1      16 1638608    88

When a system's swap space is at 100% allocation, an application's memory pages become temporarily locked. Application errors might not occur, but system performance will likely suffer.

For information on adding more swap space to your system, see How to Create a Swap File and Make It Available in UFS Root Environment.

Swap-Related Error Messages

These messages indicate that an application was trying to get more anonymous memory. However, no swap space was left to back it.

application is out of memory
malloc error O
messages.1:Sep 21 20:52:11 mars genunix: [ID 470503 kern.warning] 
WARNING: Sorry, no swap space to grow stack for pid 100295 (myprog)

TMPFS-Related Error Messages

The following message is displayed if a page could not be allocated when a file was being written. This problem can occur when TMPFS tries to write more than it is allowed or if currently executed programs are using a lot of memory.

directory: File system full, swap space limit exceeded

The following message means that TMPFS ran out of physical memory while attempting to create a new file or directory:

directory: File system full, memory allocation failed

For information on recovering from the TMPFS-related error messages, see tmpfs(7FS).