linux-kernel - Re: [PATCH 4/5] rust: percpu: Add pin-hole optimizations for numerics

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Message-ID: <685d97bc.050a0220.3c0bff.7a70@mx.google.com>
Date: Thu, 26 Jun 2025 11:55:56 -0700
From: Mitchell Levy <levymitchell0@...il.com>
To: "Christoph Lameter (Ampere)" <cl@...two.org>
Cc: Miguel Ojeda <ojeda@...nel.org>, Alex Gaynor <alex.gaynor@...il.com>,
	Boqun Feng <boqun.feng@...il.com>, Gary Guo <gary@...yguo.net>,
	Björn Roy Baron <bjorn3_gh@...tonmail.com>,
	Andreas Hindborg <a.hindborg@...nel.org>,
	Alice Ryhl <aliceryhl@...gle.com>, Trevor Gross <tmgross@...ch.edu>,
	Andrew Morton <akpm@...ux-foundation.org>,
	Dennis Zhou <dennis@...nel.org>, Tejun Heo <tj@...nel.org>,
	Danilo Krummrich <dakr@...nel.org>,
	Benno Lossin <lossin@...nel.org>, linux-kernel@...r.kernel.org,
	rust-for-linux@...r.kernel.org, linux-mm@...ck.org
Subject: Re: [PATCH 4/5] rust: percpu: Add pin-hole optimizations for numerics

On Wed, Jun 25, 2025 at 10:23:42AM -0700, Christoph Lameter (Ampere) wrote:
> On Tue, 24 Jun 2025, Mitchell Levy wrote:
> 
> > +                        concat!("add gs:[{off}], {val:", $reg, "}"),
> 
> > +                        concat!("sub gs:[{off}], {val:", $reg, "}"),
> 
> > +                        concat!("sub gs:[{off}], {val}"),
> 
> Where are the other RMV instructions like this_cpu_xchg and
> this_cpu_cmpxchg, this_cpu_cmpxchg_double etc?

I wanted to stick with (what I saw as) the most basic operations for the
first submission. That said, I tried to design things such that adding
more operations should be straightforward. Happy to build on this
further for a v2 if folks are interested in that.