From: "Christoph Lameter (Ampere)" <cl@gentwo.org>
To: Tejun Heo <tj@kernel.org>
Cc: Yang Shi <shy828301@gmail.com>,
lsf-pc@lists.linux-foundation.org, Linux MM <linux-mm@kvack.org>,
dennis@kernel.org, urezki@gmail.com,
Catalin Marinas <catalin.marinas@arm.com>,
Will Deacon <will@kernel.org>,
Ryan Roberts <ryan.roberts@arm.com>,
Yang Shi <yang@os.amperecomputing.com>
Subject: Re: [LSF/MM/BPF TOPIC] Improve this_cpu_ops performance for ARM64 (and potentially other architectures)
Date: Wed, 11 Feb 2026 15:39:02 -0800 (PST) [thread overview]
Message-ID: <c6ef0444-9423-4026-5a3f-123183246ddb@gentwo.org> (raw)
In-Reply-To: <aY0Q7QhGDKwKk2ie@slm.duckdns.org>
On Wed, 11 Feb 2026, Tejun Heo wrote:
> One property that this breaks is per_cpu_ptr() of a given CPU disagreeing
> with this_cpu_ptr(). e.g. If there are users that take this_cpu_ptr() and
> uses that outside preempt disable block (which is a bit odd but allowed),
this_cpu_ptr converts a percpu variable offset to a normal pointer that
can be used without preemption.
If the scheduler changes the cpu then you would remotely access that per
cpu data in a remote cpu. Read only acces is fine. Writing could be dicey
in some cases.
> Generally sounds like a great solution for !x86.
Thanks.
next prev parent reply other threads:[~2026-02-11 23:39 UTC|newest]
Thread overview: 21+ messages / expand[flat|nested] mbox.gz Atom feed top
2026-02-11 23:14 Yang Shi
2026-02-11 23:29 ` Tejun Heo
2026-02-11 23:39 ` Christoph Lameter (Ampere) [this message]
2026-02-11 23:40 ` Tejun Heo
2026-02-12 0:05 ` Christoph Lameter (Ampere)
2026-02-11 23:58 ` Yang Shi
2026-02-12 17:54 ` Catalin Marinas
2026-02-12 18:43 ` Catalin Marinas
2026-02-13 0:23 ` Yang Shi
2026-02-12 18:45 ` Ryan Roberts
2026-02-12 19:36 ` Catalin Marinas
2026-02-12 21:12 ` Ryan Roberts
2026-02-16 10:37 ` Catalin Marinas
2026-02-18 8:59 ` Ryan Roberts
2026-02-12 18:41 ` Ryan Roberts
2026-02-12 18:55 ` Christoph Lameter (Ampere)
2026-02-12 18:58 ` Ryan Roberts
2026-02-13 18:42 ` Yang Shi
2026-02-16 11:39 ` Catalin Marinas
2026-02-17 17:28 ` Christoph Lameter (Ampere)
2026-02-18 9:18 ` Ryan Roberts
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