p.pcs = make(map[uint64]Frame)
	p.inlineStringsMapping = make(map[string]int)

	if err := p.collectBatchesAndCPUSamples(); err != nil {
		return Trace{}, err
	}

	events, err := p.parseEventBatches()
	if err != nil {
		return Trace{}, err
	}

	if p.ticksPerSec == 0 {
		return Trace{}, errors.New("no EvFrequency event")
	}

	if events.Len() > 0 {
		// Translate cpu ticks to real time.