swpd: the amount of virtual memory used (kB).
free: the amount of idle memory (kB).
buff: the amount of memory used as buffers (kB).
+cache: the amount of memory used as cache (kB).
+inact: the amount of inactive memory (kB). (-a option)
+active: the amount of active memory (kB). (-a option)
.fi
.PP
.SS
.SS
.B "IO"
.nf
-bi: Blocks sent to a block device (blocks/s).
-bo: Blocks received from a block device (blocks/s).
+bi: Blocks received from a block device (blocks/s).
+bo: Blocks sent to a block device (blocks/s).
.fi
.PP
.SS