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**-t**, **--trace** \[*file*] 26 27 Save the stopped trace to [*file|timerlat_trace.txt*]. 28 29**--dma-latency** *us* 30 Set the /dev/cpu_dma_latency to *us*, aiming to bound exit from idle latencies. 31 *cyclictest* sets this value to *0* by default, use **--dma-latency** *0* to have 32 similar results. 33 34**--deepest-idle-state** *n* 35 Disable idle states higher than *n* for cpus that are running timerlat threads to 36 reduce exit from idle latencies. If *n* is -1, all idle states are disabled. 37 On exit from timerlat, the idle state setting is restored to its original state 38 before running timerlat. 39 40 Requires rtla to be built with libcpupower. 41 42**-k**, **--kernel-threads** 43 44 Use timerlat kernel-space threads, in contrast of **-u**. 45 46**-u**, **--user-threads** 47 48 Set timerlat to run without a workload, and then dispatches user-space workloads 49 to wait on the timerlat_fd. Once the workload is awakes, it goes to sleep again 50 adding so the measurement for the kernel-to-user and user-to-kernel to the tracer 51 output. **--user-threads** will be used unless the user specify **-k**. 52 53**-U**, **--user-load** 54 55 Set timerlat to run without workload, waiting for the user to dispatch a per-cpu 56 task that waits for a new period on the tracing/osnoise/per_cpu/cpu$ID/timerlat_fd. 57 See linux/tools/rtla/sample/timerlat_load.py for an example of user-load code. 58 59**--on-threshold** *action* 60 61 Defines an action to be executed when tracing is stopped on a latency threshold 62 specified by **-i/--irq** or **-T/--thread**. 63 64 Multiple --on-threshold actions may be specified, and they will be executed in 65 the order they are provided. If any action fails, subsequent actions in the list 66 will not be executed. 67 68 Supported actions are: 69 70 - *trace[,file=<filename>]* 71 72 Saves trace output, optionally taking a filename. Alternative to -t/--trace. 73 Note that nlike -t/--trace, specifying this multiple times will result in 74 the trace being saved multiple times. 75 76 - *signal,num=<sig>,pid=<pid>* 77 78 Sends signal to process. "parent" might be specified in place of pid to target 79 the parent process of rtla. 80 81 - *shell,command=<command>* 82 83 Execute shell command. 84 85 - *continue* 86 87 Continue tracing after actions are executed instead of stopping. 88 89 Example: 90 91 $ rtla timerlat -T 20 --on-threshold trace 92 --on-threshold shell,command="grep ipi_send timerlat_trace.txt" 93 --on-threshold signal,num=2,pid=parent 94 95 This will save a trace with the default filename "timerlat_trace.txt", print its 96 lines that contain the text "ipi_send" on standard output, and send signal 2 97 (SIGINT) to the parent process. 98 99 Performance Considerations: 100 101 For time-sensitive actions, it is recommended to run **rtla timerlat** with BPF 102 support and RT priority. Note that due to implementational limitations, actions 103 might be delayed up to one second after tracing is stopped if BPF mode is not 104 available or disabled. 105 106**--on-end** *action* 107 108 Defines an action to be executed at the end of **rtla timerlat** tracing. 109 110 Multiple --on-end actions can be specified, and they will be executed in the order 111 they are provided. If any action fails, subsequent actions in the list will not be 112 executed. 113 114 See the documentation for **--on-threshold** for the list of supported actions, with 115 the exception that *continue* has no effect. 116 117 Example: 118 119 $ rtla timerlat -d 5s --on-end trace 120 121 This runs rtla timerlat with default options and save trace output at the end. 122