What does it mean if we see swpq-sz > 150 and %swpocc at 100%? (Doc ID 1951933.1)

Last updated on JULY 29, 2016

Applies to:

Solaris Operating System - Version 8.0 and later
Information in this document applies to any platform.

Goal

Why do we see permanently swpocc at 100% in sar?

# sar -q

SunOS svgr8n01 5.10 Generic_150401-05 i86pc    11/24/2014

00:00:00 runq-sz %runocc swpq-sz %swpocc
14:30:00     1.5      18   201.9     100
14:40:00     1.5      22   201.0     100
14:50:00     1.3      16   201.0     100

Average      1.5      17   200.1     100

Solaris will swap out threads in case of a memory shortage and these threads will be listed on the swap queue.

sar -q will show the length of the swap queue (swpg-sz) and a percent value for swpocc :

--------------------------------------------------------------------------------
sar(1)
--------------------------------------------------------------------------------
    -q             Reports average queue length while  occupied,
                    and percent of time occupied:

                    runq-sz, %runocc    Run   queue   of   kernel
                                        threads   in  memory  and
                                        runnable


                    swpq-sz, %swpocc    Swap queue of processes
--------------------------------------------------------------------------------

swpocc is part of the sysinfo structure. The value will be checked and updated every second among others like runque, runocc etc.

If the value for %swpocc is constantly at 100% it is nothing to worry about. As it only means, that we have at least 1 thread in the swap queue during the measured interval.

Solution

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