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Date: Wed, 4 Feb 2026 14:00:27 +0100
From: Peter Zijlstra <peterz@infradead.org>
To: Gary Guo <gary@garyguo.net>
Cc: Lyude Paul <lyude@redhat.com>, rust-for-linux@vger.kernel.org,
	linux-kernel@vger.kernel.org, Thomas Gleixner <tglx@linutronix.de>,
	Boqun Feng <boqun.feng@gmail.com>,
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	=?iso-8859-1?Q?Bj=F6rn?= Roy Baron <bjorn3_gh@protonmail.com>,
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	Ingo Molnar <mingo@redhat.com>, Will Deacon <will@kernel.org>,
	Waiman Long <longman@redhat.com>,
	Joel Fernandes <joelagnelf@nvidia.com>
Subject: Re: [PATCH v17 02/16] preempt: Track NMI nesting to separate per-CPU
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In-Reply-To: <DG66HSCEA3XP.36DNV6A9HRNOK@garyguo.net>

On Wed, Feb 04, 2026 at 12:32:45PM +0000, Gary Guo wrote:
> On Wed Feb 4, 2026 at 11:12 AM GMT, Peter Zijlstra wrote:
> > On Tue, Feb 03, 2026 at 01:15:21PM +0100, Peter Zijlstra wrote:
> >> But I'm really somewhat sad that 64bit can't do better than this.
> >
> > Here, the below builds and boots (albeit with warnings because printf
> > format crap sucks).
> 
> Hi Peter,
> 
> I am not sure if it's worth the complexity to do this for the NMI code path.
> I don't think NMI code path is hot enough that this is necessary?

Perf uses NMI. Also, the 64bit code is actually simpler.