Addressing PR feedback

- Updated README/CHANGELOG
- Added links to further info to input README
- Reduced lines to 80 chars

CHANGELOG.md

@@ -51,6 +51,7 @@ to "stdout".
 ### Features
 
 - [#1173](https://github.com/influxdata/telegraf/pull/1173): varnish input plugin. Thanks @sfox-xmatters!
+- [#1165](https://github.com/influxdata/telegraf/pull/1165): vmstat input plugin. Thanks @jshim-xm!
 - [#1138](https://github.com/influxdata/telegraf/pull/1138): nstat input plugin. Thanks @Maksadbek!
 - [#1139](https://github.com/influxdata/telegraf/pull/1139): instrumental output plugin. Thanks @jasonroelofs!
 - [#1172](https://github.com/influxdata/telegraf/pull/1172): Ceph storage stats. Thanks @robinpercy!

README.md

@@ -205,6 +205,7 @@ Currently implemented sources:
     * swap
     * processes
     * kernel (/proc/stat)
+    * kernel (/proc/vmstat)
 
 Telegraf can also collect metrics via the following service plugins:
 

plugins/inputs/system/KERNEL_VMSTAT_README.md

@@ -1,12 +1,11 @@
 # Kernel VMStat Input Plugin
 
-This plugin is only available on Linux.
+The kernel_vmstat plugin gathers virtual memory statistics 
+by reading /proc/vmstat. For a full list of available fields see the 
+/proc/vmstat section of the [proc man page](http://man7.org/linux/man-pages/man5/proc.5.html).
+For a better idea of what each field represents, see the 
+[vmstat man page](http://linux.die.net/man/8/vmstat).
 
-The kernel_vmstat plugin gathers info about the kernel that doesn't fit into other
-plugins. In general, it is the statistics available in `/proc/vmstat` that are
-not covered by other plugins.
-
-The metrics are documented in `man proc` under the `/proc/vmstat` section.
 
 ```
 /proc/vmstat

plugins/inputs/system/kernel_vmstat.go

@@ -13,102 +13,6 @@ import (
 	"github.com/influxdata/telegraf/plugins/inputs"
 )
 
-// /proc/vmstat file line prefixes to gather stats on.
-// This is currently not being used as we are retrieving all the stats. Left here for references.
-var (
-	nr_free_pages                 = []byte("nr_free_pages")
-	nr_inactive_anon              = []byte("nr_inactive_anon")
-	nr_active_anon                = []byte("nr_active_anon")
-	nr_inactive_file              = []byte("nr_inactive_file")
-	nr_active_file                = []byte("nr_active_file")
-	nr_unevictable                = []byte("nr_unevictable")
-	nr_mlock                      = []byte("nr_mlock")
-	nr_anon_pages                 = []byte("nr_anon_pages")
-	nr_mapped                     = []byte("nr_mapped")
-	nr_file_pages                 = []byte("nr_file_pages")
-	nr_dirty                      = []byte("nr_dirty")
-	nr_writeback                  = []byte("nr_writeback")
-	nr_slab_reclaimable           = []byte("nr_slab_reclaimable")
-	nr_slab_unreclaimable         = []byte("nr_slab_unreclaimable")
-	nr_page_table_pages           = []byte("nr_page_table_pages")
-	nr_kernel_stack               = []byte("nr_kernel_stack")
-	nr_unstable                   = []byte("nr_unstable")
-	nr_bounce                     = []byte("nr_bounce")
-	nr_vmscan_write               = []byte("nr_vmscan_write")
-	nr_writeback_temp             = []byte("nr_writeback_temp")
-	nr_isolated_anon              = []byte("nr_isolated_anon")
-	nr_isolated_file              = []byte("nr_isolated_file")
-	nr_shmem                      = []byte("nr_shmem")
-	numa_hit                      = []byte("numa_hit")
-	numa_miss                     = []byte("numa_miss")
-	numa_foreign                  = []byte("numa_foreign")
-	numa_interleave               = []byte("numa_interleave")
-	numa_local                    = []byte("numa_local")
-	numa_other                    = []byte("numa_other")
-	nr_anon_transparent_hugepages = []byte("nr_anon_transparent_hugepages")
-	pgpgin                        = []byte("pgpgin")
-	pgpgout                       = []byte("pgpgout")
-	pswpin                        = []byte("pswpin")
-	pswpout                       = []byte("pswpout")
-	pgalloc_dma                   = []byte("pgalloc_dma")
-	pgalloc_dma32                 = []byte("pgalloc_dma32")
-	pgalloc_normal                = []byte("pgalloc_normal")
-	pgalloc_movable               = []byte("pgalloc_movable")
-	pgfree                        = []byte("pgfree")
-	pgactivate                    = []byte("pgactivate")
-	pgdeactivate                  = []byte("pgdeactivate")
-	pgfault                       = []byte("pgfault")
-	pgmajfault                    = []byte("pgmajfault")
-	pgrefill_dma                  = []byte("pgrefill_dma")
-	pgrefill_dma32                = []byte("pgrefill_dma32")
-	pgrefill_normal               = []byte("pgrefill_normal")
-	pgrefill_movable              = []byte("pgrefill_movable")
-	pgsteal_dma                   = []byte("pgsteal_dma")
-	pgsteal_dma32                 = []byte("pgsteal_dma32")
-	pgsteal_normal                = []byte("pgsteal_normal")
-	pgsteal_movable               = []byte("pgsteal_movable")
-	pgscan_kswapd_dma             = []byte("pgscan_kswapd_dma")
-	pgscan_kswapd_dma32           = []byte("pgscan_kswapd_dma32")
-	pgscan_kswapd_normal          = []byte("pgscan_kswapd_normal")
-	pgscan_kswapd_movable         = []byte("pgscan_kswapd_movable")
-	pgscan_direct_dma             = []byte("pgscan_direct_dma")
-	pgscan_direct_dma32           = []byte("pgscan_direct_dma32")
-	pgscan_direct_normal          = []byte("pgscan_direct_normal")
-	pgscan_direct_movable         = []byte("pgscan_direct_movable")
-	zone_reclaim_failed           = []byte("zone_reclaim_failed")
-	pginodesteal                  = []byte("pginodesteal")
-	slabs_scanned                 = []byte("slabs_scanned")
-	kswapd_steal                  = []byte("kswapd_steal")
-	kswapd_inodesteal             = []byte("kswapd_inodesteal")
-	kswapd_low_wmark_hit_quickly  = []byte("kswapd_low_wmark_hit_quickly")
-	kswapd_high_wmark_hit_quickly = []byte("kswapd_high_wmark_hit_quickly")
-	kswapd_skip_congestion_wait   = []byte("kswapd_skip_congestion_wait")
-	pageoutrun                    = []byte("pageoutrun")
-	allocstall                    = []byte("allocstall")
-	pgrotated                     = []byte("pgrotated")
-	compact_blocks_moved          = []byte("compact_blocks_moved")
-	compact_pages_moved           = []byte("compact_pages_moved")
-	compact_pagemigrate_failed    = []byte("compact_pagemigrate_failed")
-	compact_stall                 = []byte("compact_stall")
-	compact_fail                  = []byte("compact_fail")
-	compact_success               = []byte("compact_success")
-	htlb_buddy_alloc_success      = []byte("htlb_buddy_alloc_success")
-	htlb_buddy_alloc_fail         = []byte("htlb_buddy_alloc_fail")
-	unevictable_pgs_culled        = []byte("unevictable_pgs_culled")
-	unevictable_pgs_scanned       = []byte("unevictable_pgs_scanned")
-	unevictable_pgs_rescued       = []byte("unevictable_pgs_rescued")
-	unevictable_pgs_mlocked       = []byte("unevictable_pgs_mlocked")
-	unevictable_pgs_munlocked     = []byte("unevictable_pgs_munlocked")
-	unevictable_pgs_cleared       = []byte("unevictable_pgs_cleared")
-	unevictable_pgs_stranded      = []byte("unevictable_pgs_stranded")
-	unevictable_pgs_mlockfreed    = []byte("unevictable_pgs_mlockfreed")
-	thp_fault_alloc               = []byte("thp_fault_alloc")
-	thp_fault_fallback            = []byte("thp_fault_fallback")
-	thp_collapse_alloc            = []byte("thp_collapse_alloc")
-	thp_collapse_alloc_failed     = []byte("thp_collapse_alloc_failed")
-	thp_split                     = []byte("thp_split")
-)
-
 type KernelVmstat struct {
 	statFile string
 }
@@ -132,7 +36,8 @@ func (k *KernelVmstat) Gather(acc telegraf.Accumulator) error {
 	dataFields := bytes.Fields(data)
 	for i, field := range dataFields {
 
-		// dataFields is an array of {"stat1_name", "stat1_value", "stat2_name", "stat2_value", ...}
+		// dataFields is an array of {"stat1_name", "stat1_value", "stat2_name",
+		// "stat2_value", ...}
 		// We only want the even number index as that contain the stat name.
 		if i%2 == 0 {
 			// Convert the stat value into an integer.