81 lines
2.0 KiB
Go
81 lines
2.0 KiB
Go
// +build linux
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/*
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Copyright The containerd Authors.
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Licensed under the Apache License, Version 2.0 (the "License");
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you may not use this file except in compliance with the License.
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You may obtain a copy of the License at
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http://www.apache.org/licenses/LICENSE-2.0
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Unless required by applicable law or agreed to in writing, software
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distributed under the License is distributed on an "AS IS" BASIS,
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WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
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See the License for the specific language governing permissions and
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limitations under the License.
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*/
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package sys
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import (
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"bufio"
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"fmt"
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"os"
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"strconv"
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"strings"
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"github.com/opencontainers/runc/libcontainer/system"
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)
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const nanoSecondsPerSecond = 1e9
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var clockTicksPerSecond = uint64(system.GetClockTicks())
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// GetSystemCPUUsage returns the host system's cpu usage in
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// nanoseconds. An error is returned if the format of the underlying
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// file does not match.
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//
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// Uses /proc/stat defined by POSIX. Looks for the cpu
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// statistics line and then sums up the first seven fields
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// provided. See `man 5 proc` for details on specific field
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// information.
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func GetSystemCPUUsage() (uint64, error) {
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var line string
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f, err := os.Open("/proc/stat")
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if err != nil {
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return 0, err
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}
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bufReader := bufio.NewReaderSize(nil, 128)
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defer func() {
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bufReader.Reset(nil)
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f.Close()
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}()
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bufReader.Reset(f)
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err = nil
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for err == nil {
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line, err = bufReader.ReadString('\n')
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if err != nil {
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break
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}
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parts := strings.Fields(line)
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switch parts[0] {
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case "cpu":
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if len(parts) < 8 {
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return 0, fmt.Errorf("bad format of cpu stats")
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}
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var totalClockTicks uint64
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for _, i := range parts[1:8] {
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v, err := strconv.ParseUint(i, 10, 64)
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if err != nil {
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return 0, fmt.Errorf("error parsing cpu stats")
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}
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totalClockTicks += v
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}
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return (totalClockTicks * nanoSecondsPerSecond) /
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clockTicksPerSecond, nil
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}
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}
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return 0, fmt.Errorf("bad stats format")
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}
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