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// 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 procfs
import (
"bufio"
"errors"
"os"
"regexp"
"strconv"
)
var (
cpuLineRE = regexp.MustCompile(`cpu(\d+) (\d+) (\d+) (\d+) (\d+) (\d+) (\d+) (\d+) (\d+) (\d+)`)
procLineRE = regexp.MustCompile(`(\d+) (\d+) (\d+)`)
)
// Schedstat contains scheduler statistics from /proc/schedstat
//
// See
// https://www.kernel.org/doc/Documentation/scheduler/sched-stats.txt
// for a detailed description of what these numbers mean.
//
// Note the current kernel documentation claims some of the time units are in
// jiffies when they are actually in nanoseconds since 2.6.23 with the
// introduction of CFS. A fix to the documentation is pending. See
// https://lore.kernel.org/patchwork/project/lkml/list/?series=403473
type Schedstat struct {
CPUs []*SchedstatCPU
}
// SchedstatCPU contains the values from one "cpu<N>" line
type SchedstatCPU struct {
CPUNum string
RunningNanoseconds uint64
WaitingNanoseconds uint64
RunTimeslices uint64
}
// ProcSchedstat contains the values from /proc/<pid>/schedstat
type ProcSchedstat struct {
RunningNanoseconds uint64
WaitingNanoseconds uint64
RunTimeslices uint64
}
// Schedstat reads data from /proc/schedstat
func (fs FS) Schedstat() (*Schedstat, error) {
file, err := os.Open(fs.proc.Path("schedstat"))
if err != nil {
return nil, err
}
defer file.Close()
stats := &Schedstat{}
scanner := bufio.NewScanner(file)
for scanner.Scan() {
match := cpuLineRE.FindStringSubmatch(scanner.Text())
if match != nil {
cpu := &SchedstatCPU{}
cpu.CPUNum = match[1]
cpu.RunningNanoseconds, err = strconv.ParseUint(match[8], 10, 64)
if err != nil {
continue
}
cpu.WaitingNanoseconds, err = strconv.ParseUint(match[9], 10, 64)
if err != nil {
continue
}
cpu.RunTimeslices, err = strconv.ParseUint(match[10], 10, 64)
if err != nil {
continue
}
stats.CPUs = append(stats.CPUs, cpu)
}
}
return stats, nil
}
func parseProcSchedstat(contents string) (stats ProcSchedstat, err error) {
match := procLineRE.FindStringSubmatch(contents)
if match != nil {
stats.RunningNanoseconds, err = strconv.ParseUint(match[1], 10, 64)
if err != nil {
return
}
stats.WaitingNanoseconds, err = strconv.ParseUint(match[2], 10, 64)
if err != nil {
return
}
stats.RunTimeslices, err = strconv.ParseUint(match[3], 10, 64)
return
}
err = errors.New("could not parse schedstat")
return
}
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