Histogram output:
cat /sys/kernel/debug/tracing/events/latency/latency_irqs/hist
cat /sys/kernel/debug/tracing/events/latency/latency_preempt/hist
cat /sys/kernel/debug/tracing/events/latency/latency_critical_timings/hist
cat /sys/kernel/debug/tracing/events/latency/latency_hrtimer_interrupt/hist
Changes from v1 as per comments from Steven/Daniel
- Use single tracepoint for irq/preempt/critical timings by introducing
a trace type field to differentiate trace type in the same tracepoint.