1.. |threshold| replace:: **-a/--auto**, **-i/--irq**, or **-T/--thread** 2.. |thresharg| replace:: -T 3.. |tracer| replace:: timerlat 4 5.. |actionsperf| replace:: 6 For time-sensitive actions, it is recommended to run **rtla timerlat** with BPF 7 support and RT priority. Note that due to implementational limitations, actions 8 might be delayed up to one second after tracing is stopped if BPF mode is not 9 available or disabled. 10 11**-a**, **--auto** *us* 12 13 Set the automatic trace mode. This mode sets some commonly used options 14 while debugging the system. It is equivalent to use **-T** *us* **-s** *us* 15 **-t**. By default, *timerlat* tracer uses FIFO:95 for *timerlat* threads, 16 thus equivalent to **-P** *f:95*. 17 18**-p**, **--period** *us* 19 20 Set the *timerlat* tracer period in microseconds. 21 22**-i**, **--irq** *us* 23 24 Stop trace if the *IRQ* latency is higher than the argument in us. 25 26 This option cannot be unset. 27 28**-T**, **--thread** *us* 29 30 Stop trace if the *Thread* latency is higher than the argument in us. 31 32 This option cannot be unset. 33 34**-s**, **--stack** *us* 35 36 Save the stack trace at the *IRQ* if a *Thread* latency is higher than the 37 argument in us. 38 39**-t**, **--trace** \[*file*] 40 41 Save the stopped trace to [*file|timerlat_trace.txt*]. 42 43**--dma-latency** *us* 44 Set the /dev/cpu_dma_latency to *us*, aiming to bound exit from idle latencies. 45 *cyclictest* sets this value to *0* by default, use **--dma-latency** *0* to have 46 similar results. 47 48**--deepest-idle-state** *n* 49 Disable idle states higher than *n* for cpus that are running timerlat threads to 50 reduce exit from idle latencies. If *n* is -1, all idle states are disabled. 51 On exit from timerlat, the idle state setting is restored to its original state 52 before running timerlat. 53 54 Requires rtla to be built with libcpupower. 55 56**-k**, **--kernel-threads** 57 58 Use timerlat kernel-space threads, in contrast of **-u**. 59 60**-u**, **--user-threads** 61 62 Set timerlat to run without a workload, and then dispatches user-space workloads 63 to wait on the timerlat_fd. Once the workload is awakened, it goes to sleep again 64 adding so the measurement for the kernel-to-user and user-to-kernel to the tracer 65 output. **--user-threads** will be used unless the user specify **-k**. 66 67**-U**, **--user-load** 68 69 Set timerlat to run without workload, waiting for the user to dispatch a per-cpu 70 task that waits for a new period on the tracing/osnoise/per_cpu/cpu$ID/timerlat_fd. 71 See linux/tools/rtla/example/timerlat_load.py for an example of user-load code. 72 73**--bpf-action** *bpf-program* 74 75 Loads a BPF program from an ELF file and executes it when a latency threshold is exceeded. 76 77 The BPF program must be a valid ELF file loadable with libbpf. The program must contain 78 a function named ``action_handler``, stored in an ELF section with the ``tp_`` prefix. 79 The prefix is used by libbpf to set BPF program type to BPF_PROG_TYPE_TRACEPOINT. 80 81 The program receives a ``struct trace_event_raw_timerlat_sample`` parameter 82 containing timerlat sample data. 83 84 An example is provided in ``tools/tracing/rtla/example/timerlat_bpf_action.c``. 85 This example demonstrates how to create a BPF program that prints latency information using 86 bpf_trace_printk() when a threshold is exceeded. 87 88 **Note**: BPF actions require BPF support to be available. If BPF is not available 89 or disabled, the tool falls back to tracefs mode and BPF actions are not supported. 90 91**--stack-format** *format* 92 93 Adjust the format of the stack trace printed during auto-analysis. 94 95 The supported values for *format* are: 96 97 * **truncate** Print the stack trace up to the first unknown address (default). 98 * **skip** Skip unknown addresses. 99 * **full** Print the entire stack trace, including unknown addresses. 100 101 For unknown addresses, the raw pointer is printed. 102 103**-A**, **--aligned** *us* 104 105 Align wake-up of timerlat threads to a set offset in microseconds. 106 107 The alignment will be applied when the threads wake up at the start of tracing while 108 the timer for the first cycle is armed. Each thread sets its timer to the wake-up time 109 of the previous thread plus the alignment. 110 111 This option may be used with any non-negative argument, including zero, which will 112 align threads so that they wake up all at the same time. 113