Re: [PATCH] sched: Add trace events for Proxy Execution (PE)

[Metin Kaya]

On 21/02/2024 2:23 pm, Steven Rostedt wrote:
> On Fri,  2 Feb 2024 08:33:38 +0000
> Metin Kaya <metin.kaya@xxxxxxx> wrote:
>
> > Add sched_[start, finish]_task_selection trace events to measure the
> > latency of PE patches in task selection.
> >
> > Moreover, introduce trace events for interesting events in PE:
> > 1. sched_pe_enqueue_sleeping_task: a task gets enqueued on wait queue of
> >     a sleeping task (mutex owner).
> > 2. sched_pe_cross_remote_cpu: dependency chain crosses remote CPU.
> > 3. sched_pe_task_is_migrating: mutex owner task migrates.
> >
> > New trace events can be tested via this command:
> > $ perf trace \
> >    -e sched:sched_start_task_selection \
> >    -e sched:sched_finish_task_selection \
> >    -e sched:sched_pe_enqueue_sleeping_task \
> >    -e sched:sched_pe_cross_remote_cpu \
> >    -e sched:sched_pe_task_is_migrating
> >
> > Notes:
> > 1. These trace events are not intended to merge upstream. Instead, they
> >     are only for making PE tests easier and will be converted to trace
> >     points once PE patches hit upstream.
>
> I wonder if the tracepoints should be added though? That is, not adding the
> trace_events that show up in tracefs, but just the tracepoints so that bpf
> or local modules could hook to them?

Yep, the intention is providing necessary support for modules (e.g., 
https://github.com/ARM-software/lisa/blob/main/lisa/_assets/kmodules/lisa/tp.c). 


> -- Steve
>
>
> > 2. This patch is based on John's Proxy Execution v7 patch series (see
> >     the link below) which is also available at
> >     https://github.com/johnstultz-work/linux-dev/commits/proxy-exec-v7-6.7-rc6/.
> >
> > Link: https://lore.kernel.org/linux-kernel/CANDhNCrHd+5twWVNqBAhVLfhMhkiO0KjxXBmwVgaCD4kAyFyWw@xxxxxxxxxxxxxx/