1// Copyright 2019 The Prometheus Authors
2// Licensed under the Apache License, Version 2.0 (the "License");
3// you may not use this file except in compliance with the License.
4// You may obtain a copy of the License at
5//
6// http://www.apache.org/licenses/LICENSE-2.0
7//
8// Unless required by applicable law or agreed to in writing, software
9// distributed under the License is distributed on an "AS IS" BASIS,
10// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
11// See the License for the specific language governing permissions and
12// limitations under the License.
13
14package procfs
15
16import (
17	"bufio"
18	"errors"
19	"os"
20	"regexp"
21	"strconv"
22)
23
24var (
25	cpuLineRE  = regexp.MustCompile(`cpu(\d+) (\d+) (\d+) (\d+) (\d+) (\d+) (\d+) (\d+) (\d+) (\d+)`)
26	procLineRE = regexp.MustCompile(`(\d+) (\d+) (\d+)`)
27)
28
29// Schedstat contains scheduler statistics from /proc/schedstat
30//
31// See
32// https://www.kernel.org/doc/Documentation/scheduler/sched-stats.txt
33// for a detailed description of what these numbers mean.
34//
35// Note the current kernel documentation claims some of the time units are in
36// jiffies when they are actually in nanoseconds since 2.6.23 with the
37// introduction of CFS. A fix to the documentation is pending. See
38// https://lore.kernel.org/patchwork/project/lkml/list/?series=403473
39type Schedstat struct {
40	CPUs []*SchedstatCPU
41}
42
43// SchedstatCPU contains the values from one "cpu<N>" line
44type SchedstatCPU struct {
45	CPUNum string
46
47	RunningNanoseconds uint64
48	WaitingNanoseconds uint64
49	RunTimeslices      uint64
50}
51
52// ProcSchedstat contains the values from /proc/<pid>/schedstat
53type ProcSchedstat struct {
54	RunningNanoseconds uint64
55	WaitingNanoseconds uint64
56	RunTimeslices      uint64
57}
58
59// Schedstat reads data from /proc/schedstat
60func (fs FS) Schedstat() (*Schedstat, error) {
61	file, err := os.Open(fs.proc.Path("schedstat"))
62	if err != nil {
63		return nil, err
64	}
65	defer file.Close()
66
67	stats := &Schedstat{}
68	scanner := bufio.NewScanner(file)
69
70	for scanner.Scan() {
71		match := cpuLineRE.FindStringSubmatch(scanner.Text())
72		if match != nil {
73			cpu := &SchedstatCPU{}
74			cpu.CPUNum = match[1]
75
76			cpu.RunningNanoseconds, err = strconv.ParseUint(match[8], 10, 64)
77			if err != nil {
78				continue
79			}
80
81			cpu.WaitingNanoseconds, err = strconv.ParseUint(match[9], 10, 64)
82			if err != nil {
83				continue
84			}
85
86			cpu.RunTimeslices, err = strconv.ParseUint(match[10], 10, 64)
87			if err != nil {
88				continue
89			}
90
91			stats.CPUs = append(stats.CPUs, cpu)
92		}
93	}
94
95	return stats, nil
96}
97
98func parseProcSchedstat(contents string) (ProcSchedstat, error) {
99	var (
100		stats ProcSchedstat
101		err   error
102	)
103	match := procLineRE.FindStringSubmatch(contents)
104
105	if match != nil {
106		stats.RunningNanoseconds, err = strconv.ParseUint(match[1], 10, 64)
107		if err != nil {
108			return stats, err
109		}
110
111		stats.WaitingNanoseconds, err = strconv.ParseUint(match[2], 10, 64)
112		if err != nil {
113			return stats, err
114		}
115
116		stats.RunTimeslices, err = strconv.ParseUint(match[3], 10, 64)
117		return stats, err
118	}
119
120	return stats, errors.New("could not parse schedstat")
121}
122