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Scrape CPU latency stats from /proc/schedstat (#1389)

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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>
This commit is contained in:
Phil Frost 2019-07-10 03:16:24 -04:00 • committed by Ben Kochie
commit f693a71c06
13 changed files with 297 additions and 5 deletions
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27
vendor/github.com/prometheus/procfs/fixtures.ttar generated vendored
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@ -168,6 +168,11 @@ SymlinkTo: net:[4026531993]
Path: fixtures/proc/26231/root
SymlinkTo: /
# ttar - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
Path: fixtures/proc/26231/schedstat
Lines: 1
411605849 93680043 79
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# ttar - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
Path: fixtures/proc/26231/stat
Lines: 1
26231 (vim) R 5392 7446 5392 34835 7446 4218880 32533 309516 26 82 1677 44 158 99 20 0 1 0 82375 56274944 1981 18446744073709551615 4194304 6294284 140736914091744 140736914087944 139965136429984 0 0 12288 1870679807 0 0 0 17 0 0 0 31 0 0 8391624 8481048 16420864 140736914093252 140736914093279 140736914093279 140736914096107 0
@ -300,6 +305,18 @@ Lines: 1
com.github.uiautomatorNULLBYTENULLBYTENULLBYTENULLBYTENULLBYTENULLBYTENULLBYTENULLBYTENULLBYTENULLBYTENULLBYTENULLBYTENULLBYTENULLBYTENULLBYTENULLBYTENULLBYTENULLBYTENULLBYTENULLBYTENULLBYTENULLBYTENULLBYTENULLBYTENULLBYTENULLBYTENULLBYTENULLBYTENULLBYTENULLBYTENULLBYTENULLBYTENULLBYTENULLBYTENULLBYTENULLBYTENULLBYTENULLBYTENULLBYTENULLBYTENULLBYTENULLBYTENULLBYTENULLBYTENULLBYTENULLBYTENULLBYTENULLBYTENULLBYTENULLBYTENULLBYTENULLBYTENULLBYTENULLBYTENULLBYTENULLBYTENULLBYTENULLBYTENULLBYTENULLBYTENULLBYTENULLBYTENULLBYTENULLBYTENULLBYTENULLBYTENULLBYTENULLBYTENULLBYTENULLBYTENULLBYTENULLBYTENULLBYTENULLBYTENULLBYTENULLBYTENULLBYTEEOF
Mode: 644
# ttar - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
Path: fixtures/proc/26233/schedstat
Lines: 8
____________________________________
< this is a malformed schedstat file >
------------------------------------
\ ^__^
\ (oo)\_______
(__)\ )\/\
||----w |
|| ||
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Directory: fixtures/proc/584
Mode: 755
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@ -609,6 +626,16 @@ some avg10=0.10 avg60=2.00 avg300=3.85 total=15
full avg10=0.20 avg60=3.00 avg300=4.95 total=25
Mode: 644
# ttar - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
Path: fixtures/proc/schedstat
Lines: 6
version 15
timestamp 15819019232
cpu0 498494191 0 3533438552 2553969831 3853684107 2465731542 2045936778163039 343796328169361 4767485306
domain0 00000000,00000003 212499247 210112015 1861015 1860405436 536440 369895 32599 210079416 25368550 24241256 384652 927363878 807233 6366 1647 24239609 2122447165 1886868564 121112060 2848625533 125678146 241025 1032026 1885836538 2545 12 2533 0 0 0 0 0 0 1387952561 21076581 0
cpu1 518377256 0 4155211005 2778589869 10466382 2867629021 1904686152592476 364107263788241 5145567945
domain0 00000000,00000003 217653037 215526982 1577949 1580427380 557469 393576 28538 215498444 28721913 27662819 371153 870843407 745912 5523 1639 27661180 2331056874 2107732788 111442342 652402556 123615235 196159 1045245 2106687543 2400 3 2397 0 0 0 0 0 0 1437804657 26220076 0
Mode: 644
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Path: fixtures/proc/self
SymlinkTo: 26231
# ttar - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -

9
vendor/github.com/prometheus/procfs/proc.go generated vendored
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@ -300,3 +300,12 @@ func (p Proc) FileDescriptorsInfo() (ProcFDInfos, error) {
return fdinfos, nil
}
// Schedstat returns task scheduling information for the process.
func (p Proc) Schedstat() (ProcSchedstat, error) {
contents, err := ioutil.ReadFile(p.path("schedstat"))
if err != nil {
return ProcSchedstat{}, err
}
return parseProcSchedstat(string(contents))
}

128
vendor/github.com/prometheus/procfs/schedstat.go generated vendored Normal file
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@ -0,0 +1,128 @@
// 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/schedstats
//
// See
// https://www.kernel.org/doc/Documentation/scheduler/sched-stats.txt
// for a detailed description of what these numbers mean.
type Schedstat struct {
CPUs []*SchedstatCPU
}
// SchedstatCPU contains the values from one "cpu<N>" line
type SchedstatCPU struct {
CPUNum string
RunningJiffies uint64
WaitingJiffies uint64
RunTimeslices uint64
}
// ProcSchedstat contains the values from /proc/<pid>/schedstat
type ProcSchedstat struct {
RunningJiffies uint64
WaitingJiffies uint64
RunTimeslices uint64
}
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.RunningJiffies, err = strconv.ParseUint(match[8], 10, 64)
if err != nil {
continue
}
cpu.WaitingJiffies, 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.RunningJiffies, err = strconv.ParseUint(match[1], 10, 64)
if err != nil {
return
}
stats.WaitingJiffies, 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
}
func (stat *SchedstatCPU) RunningSeconds() float64 {
return float64(stat.RunningJiffies) / userHZ
}
func (stat *SchedstatCPU) WaitingSeconds() float64 {
return float64(stat.WaitingJiffies) / userHZ
}
func (stat *ProcSchedstat) RunningSeconds() float64 {
return float64(stat.RunningJiffies) / userHZ
}
func (stat *ProcSchedstat) WaitingSeconds() float64 {
return float64(stat.WaitingJiffies) / userHZ
}