common_timerlat_description.txt

 1The **rtla timerlat** tool is an interface for the *timerlat* tracer. The
 2*timerlat* tracer dispatches a kernel thread per-cpu. These threads
 3set a periodic timer to wake themselves up and go back to sleep. After
 4the wakeup, they collect and generate useful information for the
 5debugging of operating system timer latency.
 6
 7The *timerlat* tracer outputs information in two ways. It periodically
 8prints the timer latency at the timer *IRQ* handler and the *Thread*
 9handler. It also enables the trace of the most relevant information via
10**osnoise:** tracepoints.
11
12The **rtla timerlat** tool sets the options of the *timerlat* tracer
13and collects and displays a summary of the results. By default,
14the collection is done synchronously in kernel space using a dedicated
15BPF program attached to the *timerlat* tracer. If either BPF or
16the **osnoise:timerlat_sample** tracepoint it attaches to is
17unavailable, the **rtla timerlat** tool falls back to using tracefs to
18process the data asynchronously in user space.