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The timerlat tracer provides an interface for any application to wait for the timerlat's periodic wakeup. Currently, rtla timerlat uses it to dispatch its user-space workload (-u option). But as the tracer interface is generic, rtla timerlat can also be used to monitor any workload that uses it. For example, a user might place their own workload to wait on the tracer interface, and monitor the results with rtla timerlat. Add the -U option to rtla timerlat top and hist. With this option, rtla timerlat will not dispatch its workload but only setting up the system, waiting for a user to dispatch its workload. The sample code in this patch is an example of python application that loops in the timerlat tracer fd. To use it, dispatch: # rtla timerlat -U In a terminal, then run the python program on another terminal, specifying the CPU to run it. For example, setting on CPU 1: #./timerlat_load.py 1 Then rtla timerlat will start printing the statistics of the ./timerlat_load.py app. An interesting point is that the "Ret user Timer Latency" value is the overall response time of the load. The sample load does a memory copy to exemplify that. The stop tracing options on rtla timerlat works in this setup as well, including auto analysis. Link: https://lkml.kernel.org/r/36e6bcf18fe15c7601048fd4c65aeb193c502cc8.1707229706.git.bristot@kernel.org Cc: Jonathan Corbet <corbet@lwn.net> Cc: Masami Hiramatsu <mhiramat@kernel.org> Signed-off-by: Daniel Bristot de Oliveira <bristot@kernel.org> |
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| .. | ||
| common_appendix.rst | ||
| common_hist_options.rst | ||
| common_options.rst | ||
| common_osnoise_description.rst | ||
| common_osnoise_options.rst | ||
| common_timerlat_aa.rst | ||
| common_timerlat_description.rst | ||
| common_timerlat_options.rst | ||
| common_top_options.rst | ||
| index.rst | ||
| Makefile | ||
| rtla-hwnoise.rst | ||
| rtla-osnoise-hist.rst | ||
| rtla-osnoise-top.rst | ||
| rtla-osnoise.rst | ||
| rtla-timerlat-hist.rst | ||
| rtla-timerlat-top.rst | ||
| rtla-timerlat.rst | ||
| rtla.rst | ||