node_exporter/collector/schedstat_linux.go
Phil Frost f693a71c06 Scrape CPU latency stats from /proc/schedstat (#1389)
These are useful as a direct indication of CPU contention and task
scheduler latency.

Handy references:
 - https://github.com/torvalds/linux/blob/master/Documentation/scheduler/sched-stats.txt
 - https://doc.opensuse.org/documentation/leap/tuning/html/book.sle.tuning/cha.tuning.taskscheduler.html

procfs is updated to pull in the enabling change:
https://github.com/prometheus/procfs/pull/186

Signed-off-by: Phil Frost <phil@postmates.com>
2019-07-10 09:16:24 +02:00

95 lines
2.3 KiB
Go

// Copyright 2019 The Prometheus Authors
// Licensed under the Apache License, Version 2.0 (the "License");
// you may not use this file except in compliance with the License.
// You may obtain a copy of the License at
//
// http://www.apache.org/licenses/LICENSE-2.0
//
// Unless required by applicable law or agreed to in writing, software
// distributed under the License is distributed on an "AS IS" BASIS,
// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
// See the License for the specific language governing permissions and
// limitations under the License.
package collector
import (
"fmt"
"github.com/prometheus/client_golang/prometheus"
"github.com/prometheus/procfs"
)
var (
runningSecondsTotal = prometheus.NewDesc(
prometheus.BuildFQName(namespace, "schedstat", "running_seconds_total"),
"Number of seconds CPU spent running a process.",
[]string{"cpu"},
nil,
)
waitingSecondsTotal = prometheus.NewDesc(
prometheus.BuildFQName(namespace, "schedstat", "waiting_seconds_total"),
"Number of seconds spent by processing waiting for this CPU.",
[]string{"cpu"},
nil,
)
timeslicesTotal = prometheus.NewDesc(
prometheus.BuildFQName(namespace, "schedstat", "timeslices_total"),
"Number of timeslices executed by CPU.",
[]string{"cpu"},
nil,
)
)
// NewSchedstatCollector returns a new Collector exposing task scheduler statistics
func NewSchedstatCollector() (Collector, error) {
fs, err := procfs.NewFS(*procPath)
if err != nil {
return nil, fmt.Errorf("failed to open procfs: %v", err)
}
return &schedstatCollector{fs: fs}, nil
}
type schedstatCollector struct {
fs procfs.FS
}
func init() {
registerCollector("schedstat", defaultEnabled, NewSchedstatCollector)
}
func (c *schedstatCollector) Update(ch chan<- prometheus.Metric) error {
stats, err := c.fs.Schedstat()
if err != nil {
return err
}
for _, cpu := range stats.CPUs {
ch <- prometheus.MustNewConstMetric(
runningSecondsTotal,
prometheus.CounterValue,
cpu.RunningSeconds(),
cpu.CPUNum,
)
ch <- prometheus.MustNewConstMetric(
waitingSecondsTotal,
prometheus.CounterValue,
cpu.WaitingSeconds(),
cpu.CPUNum,
)
ch <- prometheus.MustNewConstMetric(
timeslicesTotal,
prometheus.CounterValue,
float64(cpu.RunTimeslices),
cpu.CPUNum,
)
}
return nil
}