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Date: Wed, 21 Feb 2024 09:23:09 -0500
From: Steven Rostedt <rostedt@goodmis.org>
To: Metin Kaya <metin.kaya@arm.com>
Cc: linux-kernel@vger.kernel.org, John Stultz <jstultz@google.com>, Joel
 Fernandes <joelaf@google.com>, Qais Yousef <qyousef@google.com>, Ingo
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 linux-trace-kernel@vger.kernel.org
Subject: Re: [PATCH] sched: Add trace events for Proxy Execution (PE)
Message-ID: <20240221092309.00432f37@gandalf.local.home>
In-Reply-To: <20240202083338.1328060-1-metin.kaya@arm.com>
References: <20240202083338.1328060-1-metin.kaya@arm.com>
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On Fri,  2 Feb 2024 08:33:38 +0000
Metin Kaya <metin.kaya@arm.com> 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?

-- 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@mail.gmail.com/