linux-kernel - Re: [PATCH] ring-buffer: Use a housekeeping CPU to wake up waiters

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Message-ID: <20260107111935.3befc296@gandalf.local.home>
Date: Wed, 7 Jan 2026 11:19:35 -0500
From: Steven Rostedt <rostedt@...dmis.org>
To: Petr Tesarik <ptesarik@...e.com>
Cc: Masami Hiramatsu <mhiramat@...nel.org>, Mathieu Desnoyers
 <mathieu.desnoyers@...icios.com>, Sebastian Andrzej Siewior
 <bigeasy@...utronix.de>, Clark Williams <clrkwllms@...nel.org>,
 linux-kernel@...r.kernel.org, linux-trace-kernel@...r.kernel.org,
 linux-rt-devel@...ts.linux.dev
Subject: Re: [PATCH] ring-buffer: Use a housekeeping CPU to wake up waiters

On Wed, 7 Jan 2026 11:17:09 -0500
Steven Rostedt <rostedt@...dmis.org> wrote:

> Or we simply change it to:
> 
> static inline void

Actually, the above should be noinline, as it's in a slower path, and
should not be adding logic into the cache of the fast path.

-- Steve


> rb_irq_work_queue(struct rb_irq_work *irq_work)
> {
> 	int cpu;
> 
> 	/* irq_work_queue_on() is not allowed in NMI context */
> 	if (in_nmi()) {
> 		irq_work_queue(&irq_work->work, cpu);
> 		return;
> 	}
> 
> 	cpu = housekeeping_any_cpu(HK_TYPE_KERNEL_NOISE);
> 	/*
> 	 * If CPU isolation is not active, cpu is always the current
> 	 * CPU, and the following is equivallent to irq_work_queue().
> 	 */
> 	irq_work_queue_on(&irq_work->work, cpu);
> }