osMetricCreate
	osMetricReadDirent
	osMetricFdatasync
	osMetricSync

	// .... add more

	osMetricLast
)

var globalOSMetrics osMetrics

func init() {
	// Inject metrics.
	ioutilx.OsOpenFile = OpenFile
	ioutilx.OpenFileDirectIO = OpenFileDirectIO
	ioutilx.OsOpen = Open
}

type osMetrics struct {
	// All fields must be accessed atomically and aligned.
	operations [osMetricLast]uint64