schedstat.go

Documentation: github.com/prometheus/procfs

     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  
    14  package procfs
    15  
    16  import (
    17  	"bufio"
    18  	"errors"
    19  	"os"
    20  	"regexp"
    21  	"strconv"
    22  )
    23  
    24  var (
    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
    39  type Schedstat struct {
    40  	CPUs []*SchedstatCPU
    41  }
    42  
    43  // SchedstatCPU contains the values from one "cpu<N>" line.
    44  type 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`.
    53  type ProcSchedstat struct {
    54  	RunningNanoseconds uint64
    55  	WaitingNanoseconds uint64
    56  	RunTimeslices      uint64
    57  }
    58  
    59  // Schedstat reads data from `/proc/schedstat`.
    60  func (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  
    98  func 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
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