numcpu_freebsd.go

     1  // Copyright 2017 The Go Authors. All rights reserved.
     2  // Use of this source code is governed by a BSD-style
     3  // license that can be found in the LICENSE file.
     4  
     5  package main
     6  
     7  import (
     8  	"bytes"
     9  	"fmt"
    10  	"os"
    11  	"os/exec"
    12  	"regexp"
    13  	"runtime"
    14  	"strconv"
    15  	"strings"
    16  	"syscall"
    17  )
    18  
    19  var (
    20  	cpuSetRE = regexp.MustCompile(`(\d,?)+`)
    21  )
    22  
    23  func init() {
    24  	register("FreeBSDNumCPU", FreeBSDNumCPU)
    25  	register("FreeBSDNumCPUHelper", FreeBSDNumCPUHelper)
    26  }
    27  
    28  func FreeBSDNumCPUHelper() {
    29  	fmt.Printf("%d\n", runtime.NumCPU())
    30  }
    31  
    32  func FreeBSDNumCPU() {
    33  	_, err := exec.LookPath("cpuset")
    34  	if err != nil {
    35  		// Can not test without cpuset command.
    36  		fmt.Println("OK")
    37  		return
    38  	}
    39  	_, err = exec.LookPath("sysctl")
    40  	if err != nil {
    41  		// Can not test without sysctl command.
    42  		fmt.Println("OK")
    43  		return
    44  	}
    45  	cmd := exec.Command("sysctl", "-n", "kern.smp.active")
    46  	output, err := cmd.CombinedOutput()
    47  	if err != nil {
    48  		fmt.Printf("fail to launch %#q, error: %s, output: %s\n", cmd, err, output)
    49  		return
    50  	}
    51  	if !bytes.Equal(output, []byte("1\n")) {
    52  		// SMP mode deactivated in kernel.
    53  		fmt.Println("OK")
    54  		return
    55  	}
    56  
    57  	list, err := getList()
    58  	if err != nil {
    59  		fmt.Printf("%s\n", err)
    60  		return
    61  	}
    62  	err = checkNCPU(list)
    63  	if err != nil {
    64  		fmt.Printf("%s\n", err)
    65  		return
    66  	}
    67  	if len(list) >= 2 {
    68  		err = checkNCPU(list[:len(list)-1])
    69  		if err != nil {
    70  			fmt.Printf("%s\n", err)
    71  			return
    72  		}
    73  	}
    74  	fmt.Println("OK")
    75  	return
    76  }
    77  
    78  func getList() ([]string, error) {
    79  	pid := syscall.Getpid()
    80  
    81  	// Launch cpuset to print a list of available CPUs: pid <PID> mask: 0, 1, 2, 3.
    82  	cmd := exec.Command("cpuset", "-g", "-p", strconv.Itoa(pid))
    83  	output, err := cmd.CombinedOutput()
    84  	if err != nil {
    85  		return nil, fmt.Errorf("fail to execute %#q: %s", cmd, err)
    86  	}
    87  	output, _, ok := bytes.Cut(output, []byte("\n"))
    88  	if !ok {
    89  		return nil, fmt.Errorf("invalid output from %#q, '\\n' not found: %s", cmd, output)
    90  	}
    91  
    92  	_, cpus, ok := bytes.Cut(output, []byte(":"))
    93  	if !ok {
    94  		return nil, fmt.Errorf("invalid output from %#q, ':' not found: %s", cmd, output)
    95  	}
    96  
    97  	var list []string
    98  	for _, val := range bytes.Split(cpus, []byte(",")) {
    99  		index := string(bytes.TrimSpace(val))
   100  		if len(index) == 0 {
   101  			continue
   102  		}
   103  		list = append(list, index)
   104  	}
   105  	if len(list) == 0 {
   106  		return nil, fmt.Errorf("empty CPU list from %#q: %s", cmd, output)
   107  	}
   108  	return list, nil
   109  }
   110  
   111  func checkNCPU(list []string) error {
   112  	listString := strings.Join(list, ",")
   113  	if len(listString) == 0 {
   114  		return fmt.Errorf("could not check against an empty CPU list")
   115  	}
   116  
   117  	cListString := cpuSetRE.FindString(listString)
   118  	if len(cListString) == 0 {
   119  		return fmt.Errorf("invalid cpuset output '%s'", listString)
   120  	}
   121  	// Launch FreeBSDNumCPUHelper() with specified CPUs list.
   122  	cmd := exec.Command("cpuset", "-l", cListString, os.Args[0], "FreeBSDNumCPUHelper")
   123  	output, err := cmd.CombinedOutput()
   124  	if err != nil {
   125  		return fmt.Errorf("fail to launch child %#q, error: %s, output: %s", cmd, err, output)
   126  	}
   127  
   128  	// NumCPU from FreeBSDNumCPUHelper come with '\n'.
   129  	output = bytes.TrimSpace(output)
   130  	n, err := strconv.Atoi(string(output))
   131  	if err != nil {
   132  		return fmt.Errorf("fail to parse output from child %#q, error: %s, output: %s", cmd, err, output)
   133  	}
   134  	if n != len(list) {
   135  		return fmt.Errorf("runtime.NumCPU() expected to %d, got %d when run with CPU list %s", len(list), n, cListString)
   136  	}
   137  	return nil
   138  }
   139
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