The first line of
vmstat represents a summary of information since boot time.
To obtain useful real-time statistics, run
vmstat with a
time step (eg
vmstat output columns are as follows
pagesize command to determine the size
of the pages):
- procs or kthr/r: Run queue length.
- procs or kthr/b: Processes blocked while waiting for I/O.
- procs or kthr/w: Idle processes which have been swapped.
- memory/swap: Free, unreserved swap space (Kb).
- memory/free: Free memory (Kb). (Note that this will
grow until it reaches
lotsfree, at which point the page scanner is started. See "Paging" for more details.)
- page/re: Pages reclaimed from the free list. (If a page on the free list still contains data needed for a new request, it can be remapped.)
- page/mf: Minor faults (page in memory, but not mapped).
(If the page is still in memory, a minor fault remaps the page.
It is comparable to the
vfltsvalue reported by
- page/pi: Paged in from swap (Kb/s). (When a page is brought back from the swap device, the process will stop execution and wait. This may affect performance.)
- page/po: Paged out to swap (Kb/s). (The page has been written and freed. This can be the result of activity by the pageout scanner, a file close, or fsflush.)
- page/fr: Freed or destroyed (Kb/s). (This column reports the activity of the page scanner.)
- page/de: Freed after writes (Kb/s). (These pages have been freed due to a pageout.)
- page/sr: Scan rate (pages). Note that this number is not reported as a "rate," but as a total number of pages scanned.
- disk/s#: Disk activity for disk # (I/O's per second).
- faults/in: Interrupts (per second).
- faults/sy: System calls (per second).
- faults/cs: Context switches (per second).
- cpu/us: User CPU time (%).
- cpu/sy: Kernel CPU time (%).
- cpu/id: Idle + I/O wait CPU time (%).
vmstat -i reports on hardware interrupts.
vmstat -s provides a summary of memory statistics, including
statistics related to the DNLC, inode and rnode caches.
vmstat -S reports on swap-related statistics such as:
- si: Swapped in (Kb/s).
- so: Swap outs (Kb/s).
(Note that the
man page for
vmstat -s incorrectly describes the swap
queue length. In Solaris 2, the swap queue length is the number of
idle swapped-out processes. (In SunOS 4, this referred to the number
of active swapped-out processes.)
vmstatunder Solaris 8 will report different statistics than would be expected under an earlier version of Solaris due to a different paging algorithm:
- Page Reclaim rate higher.
- Higher reported Free Memory: A large component of the filesystem cache is reported as free memory.
- Low Scan Rates: Scan rates will be near zero unless there is a systemwide shortage of available memory.
vmstat -p reports paging activity details for applications
(executables), data (anonymous) and filesystem activity.