linux-kernel - Re: [PATCH v14 00/16] Refcounted interrupts, SpinLockIrq for rust

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Message-ID: <aSE64jwpOZQyVl7Q@tardis.local>
Date: Fri, 21 Nov 2025 20:24:02 -0800
From: Boqun Feng <boqun.feng@...il.com>
To: John Hubbard <jhubbard@...dia.com>
Cc: Lyude Paul <lyude@...hat.com>, rust-for-linux@...r.kernel.org,
	linux-kernel@...r.kernel.org, Thomas Gleixner <tglx@...utronix.de>,
	Daniel Almeida <daniel.almeida@...labora.com>,
	Miguel Ojeda <ojeda@...nel.org>,
	Alex Gaynor <alex.gaynor@...il.com>, Gary Guo <gary@...yguo.net>,
	Björn Roy Baron <bjorn3_gh@...tonmail.com>,
	Benno Lossin <lossin@...nel.org>,
	Andreas Hindborg <a.hindborg@...nel.org>,
	Alice Ryhl <aliceryhl@...gle.com>, Trevor Gross <tmgross@...ch.edu>,
	Danilo Krummrich <dakr@...nel.org>,
	Andrew Morton <akpm@...ux-foundation.org>,
	Peter Zijlstra <peterz@...radead.org>,
	Ingo Molnar <mingo@...hat.com>, Will Deacon <will@...nel.org>,
	Waiman Long <longman@...hat.com>
Subject: Re: [PATCH v14 00/16] Refcounted interrupts, SpinLockIrq for rust

On Fri, Nov 21, 2025 at 08:14:59PM -0800, John Hubbard wrote:
[...]
> > 
> > Lyude had tried another approach [1], which uses an unsafe public API,
> > and doesn't work (easily) with CondVar or PREEMPT_RT And that eventually
> > triggered more discussion about a better API design, and as Thomas
> > pointed out [2]: "Stop worrying about mostly irrelevant low level
> > details which are not relevant to the primary audience of rust adoption.
> > We can worry about them when we replace the scheduler and the low level
> > interrupt handling code ten years down the road." And I agreed. The
> > current implementation is actually quite efficient and should even
> > out-perform the existing API in some cases as I pointed out. More
> > importantly, it utilizes Rust type system and make it easy to use (or
> > hard to mis-use).
> > 
> > That being said, if anyone has a better idea, feel free to bring it up.
> > 
> > > I'm asking early (see above: I agree that this is "premature"), because
> > > we have early data.
> > > 
> > > It would be nice to explore now, rather than later, after someone shows
> > > up with detailed perf data about their use case.
> > > 
> > > 
> > 
> > Not sure I fully agree with this, given it's to my knowledge the best
> > solution at the moment, I feel it's hard to justify the cost of
> > exploring a better solution without a real usage. But then again, if
> > anyone has any better idea feel free to bring it up.
> > 
> > [1]: https://lore.kernel.org/rust-for-linux/20240916213025.477225-2-lyude@redhat.com/
> > [2]: https://lore.kernel.org/rust-for-linux/87iktrahld.ffs@tglx/
> > 
> 
> Thanks for this context, I hadn't followed the earlier discussions,
> and when looking at this v14, it seemed to gloss over the performance
> implications (they were linked to, but not discussed).
> 

I could have provided this earlier ;-)

> I won't further harass you all about this, let's see how it goes. :)
> 
> Optionally, it might be helpful to include some top-level notes
> that justify the choices made so far.
> 

Sure, I will keep a note on that when applying the series. Thank you!

Regards,
Boqun

> thanks,
> -- 
> John Hubbard
>