xref: /freebsd/lib/libkvm/kvm_getswapinfo.3 (revision fa9896e082a1046ff4fbc75fcba4d18d1f2efc19)

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.Dd January 2, 2017
.Dt KVM_SWAPINFO 3
.Os
.Sh NAME
.Nm kvm_getswapinfo
.Nd return swap summary statistics for the system
.Sh LIBRARY
.Lb libkvm
.Sh SYNOPSIS
.In kvm.h
.Ft int
.Fn kvm_getswapinfo "kvm_t *kd" "struct kvm_swap *" "int maxswap" "int flags"
.Sh DESCRIPTION
The
.Fn kvm_getswapinfo
function fills an array of
.Vt kvm_swap
structures with swap summary
information for each swap device, for up to
.Fa maxswap
\- 1 devices.
The number of devices, up to
.Fa maxswap
\- 1, is returned.
A grand
total of all swap devices (including any devices that go beyond
.Fa maxswap
\- 1) is returned in one additional array entry.
This
entry is not counted in the return value.
Thus, if you specify a
.Fa maxswap
value of 1, the function will typically return the
value 0 and the single
.Vt kvm_swap
structure will be filled with
the grand total over all swap devices.
The grand total is calculated
from all available swap devices whether or not you made room
for them all in the array.
The grand total is returned.
.Pp
The flags argument is currently unused and must be passed as 0.
.Pp
If an error occurs, -1 is returned.
.Pp
Each swap partition and the grand total is summarized in the
.Vt kvm_swap
structure.
This structure contains the following fields:
.Pp
.Bl -item -offset indent -compact
.It
.Va char ksw_devname[] ;
.It
.Va u_int ksw_total ;
.It
.Va u_int ksw_used ;
.It
.Va int ksw_flags ;
.El
.Pp
Values are in
.Dv PAGE_SIZE Ns 'd
chunks (see
.Xr getpagesize 3 ) .
.Va ksw_flags
contains
a copy of the swap device flags.
.Sh CACHING
This function caches the nlist values for various kernel variables which
it reuses in successive calls.
You may call the function with
.Fa kd
==
.Dv NULL
to clear the cache.
.Sh DIAGNOSTICS
If the swap summary information was unobtainable, \-1 is returned;
otherwise, the number of swap devices actually retrieved is returned.
.Pp
If the name of the swap device does not fit in the static char buffer
in the structure, it is truncated.
The buffer is always zero terminated.
.Sh SEE ALSO
.Xr kvm 3