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Diffstat (limited to 'Documentation/tools/rtla/common_timerlat_description.txt')
| -rw-r--r-- | Documentation/tools/rtla/common_timerlat_description.txt | 18 |
1 files changed, 18 insertions, 0 deletions
diff --git a/Documentation/tools/rtla/common_timerlat_description.txt b/Documentation/tools/rtla/common_timerlat_description.txt new file mode 100644 index 000000000000..49fcae3ffdec --- /dev/null +++ b/Documentation/tools/rtla/common_timerlat_description.txt @@ -0,0 +1,18 @@ +The **rtla timerlat** tool is an interface for the *timerlat* tracer. The +*timerlat* tracer dispatches a kernel thread per-cpu. These threads +set a periodic timer to wake themselves up and go back to sleep. After +the wakeup, they collect and generate useful information for the +debugging of operating system timer latency. + +The *timerlat* tracer outputs information in two ways. It periodically +prints the timer latency at the timer *IRQ* handler and the *Thread* +handler. It also enables the trace of the most relevant information via +**osnoise:** tracepoints. + +The **rtla timerlat** tool sets the options of the *timerlat* tracer +and collects and displays a summary of the results. By default, +the collection is done synchronously in kernel space using a dedicated +BPF program attached to the *timerlat* tracer. If either BPF or +the **osnoise:timerlat_sample** tracepoint it attaches to is +unavailable, the **rtla timerlat** tool falls back to using tracefs to +process the data asynchronously in user space. |