prevDriveIOStatsMu.Lock()
		if prevDriveIOStats != nil {
			duration := now.Sub(prevDriveIOStatsRefreshedAt)
			if duration.Seconds() > 1 {
				for d, cs := range currentStats {
					if ps, found := prevDriveIOStats[d]; found {
						v.ioStats[d] = getDriveIOStatMetrics(getDiffStats(ps, cs), duration)
					}
				}
			}
		}

		prevDriveIOStats = currentStats
		prevDriveIOStatsRefreshedAt = now
		prevDriveIOStatsMu.Unlock()

Harshavardhana <******@****.***> <******@****.***>
Harshavardhana <******@****.***> <******@****.***>
Harshavardhana <******@****.***>
Krishna Srinivas <******@****.***> <******@****.***>
Matthew Farrellee <matt@cs.wisc.edu>