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770840a0e7
Add dependencies needed to build rtla with BPF sample collection support to README, and document both ways of sample collection in the manpages. Signed-off-by: Tomas Glozar <tglozar@redhat.com> Acked-by: Steven Rostedt (Google) <rostedt@goodmis.org> Reviewed-by: Luis Claudio R. Goncalves <lgoncalv@redhat.com> Signed-off-by: Jonathan Corbet <corbet@lwn.net> Link: https://lore.kernel.org/r/20250311114936.148012-5-tglozar@redhat.com
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18 lines
1,010 B
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The **rtla timerlat** tool is an interface for the *timerlat* tracer. The
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*timerlat* tracer dispatches a kernel thread per-cpu. These threads
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set a periodic timer to wake themselves up and go back to sleep. After
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the wakeup, they collect and generate useful information for the
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debugging of operating system timer latency.
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The *timerlat* tracer outputs information in two ways. It periodically
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prints the timer latency at the timer *IRQ* handler and the *Thread*
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handler. It also enables the trace of the most relevant information via
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**osnoise:** tracepoints.
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The **rtla timerlat** tool sets the options of the *timerlat* tracer
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and collects and displays a summary of the results. By default,
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the collection is done synchronously in kernel space using a dedicated
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BPF program attached to the *timerlat* tracer. If either BPF or
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the **osnoise:timerlat_sample** tracepoint it attaches to is
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unavailable, the **rtla timerlat** tool falls back to using tracefs to
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process the data asynchronously in user space.
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