Re: [PATCH V4 05/19] trace/osnoise: Allow multiple instances of the same tracer

On 10/23/21 04:47, Steven Rostedt wrote:

On Thu, 21 Oct 2021 14:56:43 +0200
Daniel Bristot de Oliveira [off-list ref] wrote:

quoted

Allow more than one instance of the same tracer. The workload will
start when the first trace_array (instance) is registered and will
stop when the last instance is unregistered.

quoted

Osnoise and timerlat are still mutually exclusive because of the
different behavior of the osnoise: tracepoints.

I don't understand what the above means, or how it is relative to this
commit?

osnoise and timerlat tracers share a lot of code, including the osnoise: events.

However, the osnoise: events have different behavior depending on which tracer
is enabled. So, while this patch allows the same tracer to run in multiple
instances (e.g., two instances running osnoise), it still does not allow
instances of timerlat and osnoise in parallel (e.g., one timerlat and osnoise).

Should I add the text above to the log?

It is possible to extend the current behavior to allow concurrent osnoise and
timerlat tracers to run on different CPUs. For instance, osnoise on cpu 0,1 and
timerlat on cpu 2,3. This is on my to-do list, but it is not necessary for now.

-- Daniel

-- Steve