xref: /linux/Documentation/tools/rtla/common_timerlat_options.rst (revision 1f20a5769446a1acae67ac9e63d07a594829a789)
1**-a**, **--auto** *us*
2
3        Set the automatic trace mode. This mode sets some commonly used options
4        while debugging the system. It is equivalent to use **-T** *us* **-s** *us*
5        **-t**. By default, *timerlat* tracer uses FIFO:95 for *timerlat* threads,
6        thus equilavent to **-P** *f:95*.
7
8**-p**, **--period** *us*
9
10        Set the *timerlat* tracer period in microseconds.
11
12**-i**, **--irq** *us*
13
14        Stop trace if the *IRQ* latency is higher than the argument in us.
15
16**-T**, **--thread** *us*
17
18        Stop trace if the *Thread* latency is higher than the argument in us.
19
20**-s**, **--stack** *us*
21
22        Save the stack trace at the *IRQ* if a *Thread* latency is higher than the
23        argument in us.
24
25**--dma-latency** *us*
26        Set the /dev/cpu_dma_latency to *us*, aiming to bound exit from idle latencies.
27        *cyclictest* sets this value to *0* by default, use **--dma-latency** *0* to have
28        similar results.
29
30**-u**, **--user-threads**
31
32        Set timerlat to run without a workload, and then dispatches user-space workloads
33        to wait on the timerlat_fd. Once the workload is awakes, it goes to sleep again
34        adding so the measurement for the kernel-to-user and user-to-kernel to the tracer
35        output.
36
37**-U**, **--user-load**
38
39        Set timerlat to run without workload, waiting for the user to dispatch a per-cpu
40        task that waits for a new period on the tracing/osnoise/per_cpu/cpu$ID/timerlat_fd.
41        See linux/tools/rtla/sample/timerlat_load.py for an example of user-load code.
42