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

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Date: Wed, 21 Feb 2024 09:23:09 -0500
From: Steven Rostedt <rostedt@...dmis.org>
To: Metin Kaya <metin.kaya@....com>
Cc: linux-kernel@...r.kernel.org, John Stultz <jstultz@...gle.com>, Joel
 Fernandes <joelaf@...gle.com>, Qais Yousef <qyousef@...gle.com>, Ingo
 Molnar <mingo@...hat.com>, Peter Zijlstra <peterz@...radead.org>, Juri
 Lelli <juri.lelli@...hat.com>, Vincent Guittot
 <vincent.guittot@...aro.org>, Dietmar Eggemann <dietmar.eggemann@....com>,
 Valentin Schneider <vschneid@...hat.com>, Masami Hiramatsu
 <mhiramat@...nel.org>, Mathieu Desnoyers <mathieu.desnoyers@...icios.com>,
 Ben Segall <bsegall@...gle.com>, Zimuzo Ezeozue <zezeozue@...gle.com>,
 Youssef Esmat <youssefesmat@...gle.com>, Mel Gorman <mgorman@...e.de>,
 Daniel Bristot de Oliveira <bristot@...hat.com>, Will Deacon
 <will@...nel.org>, Waiman Long <longman@...hat.com>, Boqun Feng
 <boqun.feng@...il.com>, "Paul E. McKenney" <paulmck@...nel.org>, Xuewen Yan
 <xuewen.yan94@...il.com>, K Prateek Nayak <kprateek.nayak@....com>, Thomas
 Gleixner <tglx@...utronix.de>, kernel-team@...roid.com,
 linux-trace-kernel@...r.kernel.org
Subject: Re: [PATCH] sched: Add trace events for Proxy Execution (PE)

On Fri,  2 Feb 2024 08:33:38 +0000
Metin Kaya <metin.kaya@....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/