From 1fd3a4dbad783cc125d162d3a413b514048bf149 Mon Sep 17 00:00:00 2001
From: kthommandra <kthommandra@arista.com>
Date: Tue, 16 Aug 2016 05:13:14 -0700
Subject: [PATCH] Added the writeback, dirty and writebacktmp fields from
 /proc/meminfo on Linux

---
 mem/mem.go       | 8 ++++++--
 mem/mem_linux.go | 6 ++++++
 mem/mem_test.go  | 2 +-
 3 files changed, 13 insertions(+), 3 deletions(-)

diff --git a/mem/mem.go b/mem/mem.go
index 3255890..a6c0123 100644
--- a/mem/mem.go
+++ b/mem/mem.go
@@ -48,8 +48,12 @@ type VirtualMemoryStat struct {
 
 	// Linux specific numbers
 	// https://www.centos.org/docs/5/html/5.1/Deployment_Guide/s2-proc-meminfo.html
-	Buffers uint64 `json:"buffers"`
-	Cached  uint64 `json:"cached"`
+	// https://www.kernel.org/doc/Documentation/filesystems/proc.txt
+	Buffers      uint64 `json:"buffers"`
+	Cached       uint64 `json:"cached"`
+	Writeback    uint64 `json:"writeback"`
+	Dirty        uint64 `json:"dirty"`
+	WritebackTmp uint64 `json:"writebacktmp"`
 }
 
 type SwapMemoryStat struct {
diff --git a/mem/mem_linux.go b/mem/mem_linux.go
index 899da83..7df4c3e 100644
--- a/mem/mem_linux.go
+++ b/mem/mem_linux.go
@@ -46,6 +46,12 @@ func VirtualMemory() (*VirtualMemoryStat, error) {
 			ret.Active = t * 1024
 		case "Inactive":
 			ret.Inactive = t * 1024
+		case "Writeback":
+			ret.Writeback = t * 1024
+		case "WritebackTmp":
+			ret.WritebackTmp = t * 1024
+		case "Dirty":
+			ret.Dirty = t * 1024
 		}
 	}
 	if !memavail {
diff --git a/mem/mem_test.go b/mem/mem_test.go
index f7074d8..21582b9 100644
--- a/mem/mem_test.go
+++ b/mem/mem_test.go
@@ -52,7 +52,7 @@ func TestVirtualMemoryStat_String(t *testing.T) {
 		UsedPercent: 30.1,
 		Free:        40,
 	}
-	e := `{"total":10,"available":20,"used":30,"usedPercent":30.1,"free":40,"active":0,"inactive":0,"wired":0,"buffers":0,"cached":0}`
+	e := `{"total":10,"available":20,"used":30,"usedPercent":30.1,"free":40,"active":0,"inactive":0,"wired":0,"buffers":0,"cached":0,"writeback":0,"dirty":0,"writebacktmp":0}`
 	if e != fmt.Sprintf("%v", v) {
 		t.Errorf("VirtualMemoryStat string is invalid: %v", v)
 	}