Add pagefault data to procstat input plugin (influxdata#5769)

Author: sgtsquiggs

plugins/inputs/procstat/README.md

@@ -85,6 +85,8 @@ implemented as a WMI query.  The pattern allows fuzzy matching using only
     - cgroup (when defined)
     - win_service (when defined)
   - fields:
+    - child_major_faults (int)
+    - child_minor_faults (int)
     - cpu_time (int)
     - cpu_time_guest (float)
     - cpu_time_guest_nice (float)
@@ -99,12 +101,14 @@ implemented as a WMI query.  The pattern allows fuzzy matching using only
     - cpu_time_user (float)
     - cpu_usage (float)
     - involuntary_context_switches (int)
+    - major_faults (int)
     - memory_data (int)
     - memory_locked (int)
     - memory_rss (int)
     - memory_stack (int)
     - memory_swap (int)
     - memory_vms (int)
+    - minor_faults (int)
     - nice_priority (int)
     - num_fds (int, *telegraf* may need to be ran as **root**)
     - num_threads (int)

plugins/inputs/procstat/process.go

@@ -12,6 +12,7 @@ type Process interface {
 	PID() PID
 	Tags() map[string]string
 
+	PageFaults() (*process.PageFaultsStat, error)
 	IOCounters() (*process.IOCountersStat, error)
 	MemoryInfo() (*process.MemoryInfoStat, error)
 	Name() (string, error)

plugins/inputs/procstat/procstat.go

@@ -200,6 +200,14 @@ func (p *Procstat) addMetric(proc Process, acc telegraf.Accumulator) {
 		fields[prefix+"involuntary_context_switches"] = ctx.Involuntary
 	}
 
+	faults, err := proc.PageFaults()
+	if err == nil {
+		fields[prefix+"minor_faults"] = faults.MinorFaults
+		fields[prefix+"major_faults"] = faults.MajorFaults
+		fields[prefix+"child_minor_faults"] = faults.ChildMinorFaults
+		fields[prefix+"child_major_faults"] = faults.ChildMajorFaults
+	}
+
 	io, err := proc.IOCounters()
 	if err == nil {
 		fields[prefix+"read_count"] = io.ReadCount

plugins/inputs/procstat/procstat_test.go

@@ -116,6 +116,10 @@ func (p *testProc) Tags() map[string]string {
 	return p.tags
 }
 
+func (p *testProc) PageFaults() (*process.PageFaultsStat, error) {
+	return &process.PageFaultsStat{}, nil
+}
+
 func (p *testProc) IOCounters() (*process.IOCountersStat, error) {
 	return &process.IOCountersStat{}, nil
 }