Merge pull request #2377 from thaJeztah/ticks_simplify

Simplify ticks, as the value is a constant

libcontainer/cgroups/fs/cpuacct.go

@@ -12,15 +12,18 @@ import (
 	"github.com/opencontainers/runc/libcontainer/cgroups"
 	"github.com/opencontainers/runc/libcontainer/cgroups/fscommon"
 	"github.com/opencontainers/runc/libcontainer/configs"
-	"github.com/opencontainers/runc/libcontainer/system"
 )
 
 const (
 	cgroupCpuacctStat   = "cpuacct.stat"
 	nanosecondsInSecond = 1000000000
-)
 
-var clockTicks = uint64(system.GetClockTicks())
+	// The value comes from `C.sysconf(C._SC_CLK_TCK)`, and
+	// on Linux it's a constant which is safe to be hard coded,
+	// so we can avoid using cgo here. For details, see:
+	// https://github.com/containerd/cgroups/pull/12
+	clockTicks uint64 = 100
+)
 
 type CpuacctGroup struct {
 }

libcontainer/system/sysconfig.go

@@ -1,12 +0,0 @@
-// +build cgo,linux
-
-package system
-
-/*
-#include <unistd.h>
-*/
-import "C"
-
-func GetClockTicks() int {
-	return int(C.sysconf(C._SC_CLK_TCK))
-}

libcontainer/system/sysconfig_notcgo.go

@@ -1,15 +0,0 @@
-// +build !cgo windows
-
-package system
-
-func GetClockTicks() int {
-	// TODO figure out a better alternative for platforms where we're missing cgo
-	//
-	// TODO Windows. This could be implemented using Win32 QueryPerformanceFrequency().
-	// https://msdn.microsoft.com/en-us/library/windows/desktop/ms644905(v=vs.85).aspx
-	//
-	// An example of its usage can be found here.
-	// https://msdn.microsoft.com/en-us/library/windows/desktop/dn553408(v=vs.85).aspx
-
-	return 100
-}