Gregg: perf sched for Linux CPU scheduler analysis

Brendan Gregg showshow to do scheduler profiling with the perf sched command."perf sched timehist was added in Linux 4.10, and shows the schedulerlatency by event, including the time the task was waiting to be woken up(wait time) and the scheduler latency after wakeup to running (schdelay). It's the scheduler latency that we're more interested intuning."