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From: Mathieu Desnoyers <mathieu.desnoyers@efficios.com>
To: Steven Rostedt <rostedt@goodmis.org>,
	"Paul E. McKenney" <paulmck@kernel.org>
Cc: Joel Fernandes <joelagnelf@nvidia.com>,
	"linux-kernel@vger.kernel.org" <linux-kernel@vger.kernel.org>,
	Sebastian Andrzej Siewior <bigeasy@linutronix.de>,
	"bpf@vger.kernel.org" <bpf@vger.kernel.org>,
	Thomas Gleixner <tglx@linutronix.de>
Subject: Re: [PATCH v3] tracing: Guard __DECLARE_TRACE() use of __DO_TRACE_CALL() with SRCU-fast
Date: Fri, 12 Dec 2025 23:19:41 -0500	[thread overview]
Message-ID: <09c76498-6a0b-4880-8a86-2a295c47c703@efficios.com> (raw)
In-Reply-To: <20251212211839.6c3e2399@fedora>

On 2025-12-12 21:18, Steven Rostedt wrote:
[...]
> 
> Thus, I'm going to keep this a PREEMPT_RT only change. If someone can
> come in and convince us that the PREEMPT_RT way is also beneficial for
> the non-RT case then we can make it consistent again. Until then, this
> change is focusing on fixing PREEMPT_RT, and that's what the patch is
> going to be limited to.

Here is one additional thing to keep in mind: although
SRCU-fast is probably quite fast (as the name implies),
last time I tried using migrate disable in a fast path
I was surprised to see verbosity of the generated assembly,
and how slow it was compared to preempt disable.

So before using migrate disable on a fast path, at least on
non-preempt-RT configs, we should carefully consider the
performance impact of migrate disable.

Thanks,

Mathieu

-- 
Mathieu Desnoyers
EfficiOS Inc.
https://www.efficios.com

  reply	other threads:[~2025-12-13  4:19 UTC|newest]

Thread overview: 20+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2025-12-08  4:20 [PATCH v3] tracing: Guard __DECLARE_TRACE() use of __DO_TRACE_CALL() with SRCU-fast Paul E. McKenney
2025-12-08  9:43 ` Steven Rostedt
2025-12-08 20:46   ` Paul E. McKenney
2025-12-09  0:38     ` Steven Rostedt
2025-12-09 22:29       ` Paul E. McKenney
2025-12-10  3:11         ` Steven Rostedt
2025-12-11 20:02 ` Joel Fernandes
2025-12-11 20:23   ` Paul E. McKenney
2025-12-12  0:12     ` Joel Fernandes
2025-12-12  0:47       ` Paul E. McKenney
2025-12-12  3:43         ` Joel Fernandes
2025-12-12  7:50           ` Paul E. McKenney
2025-12-12  9:28             ` Joel Fernandes
2025-12-12 23:10               ` Paul E. McKenney
2025-12-12 23:54                 ` Joel Fernandes
2025-12-13  0:06                   ` Paul E. McKenney
2025-12-13  2:18                     ` Steven Rostedt
2025-12-13  4:19                       ` Mathieu Desnoyers [this message]
2025-12-13  6:20                         ` Steven Rostedt
2025-12-12  1:13     ` Steven Rostedt

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