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From: Karl Mehltretter <kmehltretter@gmail.com>
To: Sebastian Andrzej Siewior <bigeasy@linutronix.de>
Cc: Peter Zijlstra <peterz@infradead.org>,
	 Thomas Gleixner <tglx@kernel.org>,
	Frederic Weisbecker <frederic@kernel.org>,
	 Clark Williams <clrkwllms@kernel.org>,
	Steven Rostedt <rostedt@goodmis.org>,
	 Boqun Feng <boqun@kernel.org>, Lyude Paul <lyude@redhat.com>,
	 Joel Fernandes <joelagnelf@nvidia.com>,
	Alexander Potapenko <glider@google.com>,
	 Marco Elver <elver@google.com>, Jonathan Corbet <corbet@lwn.net>,
	 Bradley Morgan <brads@mainlining.org>,
	linux-doc@vger.kernel.org, linux-kernel@vger.kernel.org,
	 linux-rt-devel@lists.linux.dev
Subject: Re: [PATCH v4] softirq: Preserve interrupt context during IRQ exit
Date: Tue, 29 Sep 2026 23:25:37 +0200	[thread overview]
Message-ID: <arwsK1dOHVB5KZjD@gmail.com> (raw)
In-Reply-To: <20260928082402.1iCSzDzY@linutronix.de>

On Mon, Sep 28, 2026 at 10:24:02AM +0100, Sebastian Andrzej Siewior wrote:
> could you please do
> 	(in_nmi() | hardirq_count()) == HARDIRQ_OFFSET)
> instead? This will merge NMI check into the hardirq check, dropping one
> conditional jump away.
> 

Hello Sebastian,

Good catch. With GCC it removes one conditional branch on x86-64, arm64
and arm32. On x86-64 it also uses three fewer instructions.

I will send this tweaked version soon.

Thanks for the review!

Karl

      reply	other threads:[~2026-09-29 21:25 UTC|newest]

Thread overview: 3+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2026-09-26 14:35 [PATCH v4] softirq: Preserve interrupt context during IRQ exit Karl Mehltretter
2026-09-28  8:24 ` Sebastian Andrzej Siewior
2026-09-29 21:25   ` Karl Mehltretter [this message]

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