From 4e4bdae58458931efdd71c6747804359b4e1cd77 Mon Sep 17 00:00:00 2001
From: Michael Schwarz <post@michael-schwarz.name>
Date: Wed, 7 Sep 2022 08:51:37 +0200
Subject: [PATCH] cpustatMetric.go: Use derived values instead of absolute
values
The values in /proc/stat are absolute counters related to the boot
time of the system. To obtain a utilization of the CPU, the changes
in the counters must be derived according to time. To take only the
absolute values leads to the fact that changes in the utilization,
straight with larger values, do not become visible.
---
collectors/cpustatMetric.go | 40 +++++++++++++++++++++++++++----------
1 file changed, 30 insertions(+), 10 deletions(-)
diff --git a/collectors/cpustatMetric.go b/collectors/cpustatMetric.go
index c0dcf13..3c09b83 100644
--- a/collectors/cpustatMetric.go
+++ b/collectors/cpustatMetric.go
@@ -11,6 +11,7 @@ import (
cclog "github.com/ClusterCockpit/cc-metric-collector/internal/ccLogger"
lp "github.com/ClusterCockpit/cc-metric-collector/internal/ccMetric"
+ sysconf "github.com/tklauser/go-sysconf"
)
const CPUSTATFILE = `/proc/stat`
@@ -22,9 +23,11 @@ type CpustatCollectorConfig struct {
type CpustatCollector struct {
metricCollector
config CpustatCollectorConfig
+ lastTimestamp time.Time // Store time stamp of last tick to derive values
matches map[string]int
cputags map[string]map[string]string
nodetags map[string]string
+ olddata map[string]map[string]int64
}
func (m *CpustatCollector) Init(config json.RawMessage) error {
@@ -76,36 +79,48 @@ func (m *CpustatCollector) Init(config json.RawMessage) error {
// Pre-generate tags for all CPUs
num_cpus := 0
m.cputags = make(map[string]map[string]string)
+ m.olddata = make(map[string]map[string]int64)
scanner := bufio.NewScanner(file)
for scanner.Scan() {
line := scanner.Text()
linefields := strings.Fields(line)
- if strings.HasPrefix(linefields[0], "cpu") && strings.Compare(linefields[0], "cpu") != 0 {
+ if strings.Compare(linefields[0], "cpu") == 0 {
+ m.olddata["cpu"] = make(map[string]int64)
+ for k, v := range m.matches {
+ m.olddata["cpu"][k], _ = strconv.ParseInt(linefields[v], 0, 64)
+ }
+ } else if strings.HasPrefix(linefields[0], "cpu") && strings.Compare(linefields[0], "cpu") != 0 {
cpustr := strings.TrimLeft(linefields[0], "cpu")
cpu, _ := strconv.Atoi(cpustr)
m.cputags[linefields[0]] = map[string]string{"type": "hwthread", "type-id": fmt.Sprintf("%d", cpu)}
+ m.olddata[linefields[0]] = make(map[string]int64)
+ for k, v := range m.matches {
+ m.olddata[linefields[0]][k], _ = strconv.ParseInt(linefields[v], 0, 64)
+ }
num_cpus++
}
}
+ m.lastTimestamp = time.Now()
m.init = true
return nil
}
-func (m *CpustatCollector) parseStatLine(linefields []string, tags map[string]string, output chan lp.CCMetric) {
+func (m *CpustatCollector) parseStatLine(linefields []string, tags map[string]string, output chan lp.CCMetric, now time.Time, tsdelta time.Duration) {
values := make(map[string]float64)
- total := 0.0
+ clktck, _ := sysconf.Sysconf(sysconf.SC_CLK_TCK)
for match, index := range m.matches {
if len(match) > 0 {
x, err := strconv.ParseInt(linefields[index], 0, 64)
if err == nil {
- values[match] = float64(x)
- total += values[match]
+ vdiff := x - m.olddata[linefields[0]][match]
+ m.olddata[linefields[0]][match] = x // Store new value for next run
+ values[match] = float64(vdiff) / float64(tsdelta.Seconds()) / float64(clktck)
}
}
}
- t := time.Now()
+
for name, value := range values {
- y, err := lp.New(name, tags, m.meta, map[string]interface{}{"value": (value * 100.0) / total}, t)
+ y, err := lp.New(name, tags, m.meta, map[string]interface{}{"value": value * 100}, now)
if err == nil {
output <- y
}
@@ -117,6 +132,9 @@ func (m *CpustatCollector) Read(interval time.Duration, output chan lp.CCMetric)
return
}
num_cpus := 0
+ now := time.Now()
+ tsdelta := now.Sub(m.lastTimestamp)
+
file, err := os.Open(string(CPUSTATFILE))
if err != nil {
cclog.ComponentError(m.name, err.Error())
@@ -128,9 +146,9 @@ func (m *CpustatCollector) Read(interval time.Duration, output chan lp.CCMetric)
line := scanner.Text()
linefields := strings.Fields(line)
if strings.Compare(linefields[0], "cpu") == 0 {
- m.parseStatLine(linefields, m.nodetags, output)
+ m.parseStatLine(linefields, m.nodetags, output, now, tsdelta)
} else if strings.HasPrefix(linefields[0], "cpu") {
- m.parseStatLine(linefields, m.cputags[linefields[0]], output)
+ m.parseStatLine(linefields, m.cputags[linefields[0]], output, now, tsdelta)
num_cpus++
}
}
@@ -139,11 +157,13 @@ func (m *CpustatCollector) Read(interval time.Duration, output chan lp.CCMetric)
m.nodetags,
m.meta,
map[string]interface{}{"value": int(num_cpus)},
- time.Now(),
+ now,
)
if err == nil {
output <- num_cpus_metric
}
+
+ m.lastTimestamp = now
}
func (m *CpustatCollector) Close() {