From: Catalin Marinas <catalin.marinas@arm.com>
To: Ankur Arora <ankur.a.arora@oracle.com>
Cc: linux-kernel@vger.kernel.org, linux-arch@vger.kernel.org,
linux-arm-kernel@lists.infradead.org, bpf@vger.kernel.org,
arnd@arndb.de, will@kernel.org, peterz@infradead.org,
akpm@linux-foundation.org, mark.rutland@arm.com,
harisokn@amazon.com, cl@gentwo.org, ast@kernel.org,
memxor@gmail.com, zhenglifeng1@huawei.com,
xueshuai@linux.alibaba.com, joao.m.martins@oracle.com,
boris.ostrovsky@oracle.com, konrad.wilk@oracle.com
Subject: Re: [PATCH v4 1/5] asm-generic: barrier: Add smp_cond_load_relaxed_timewait()
Date: Mon, 1 Sep 2025 12:29:59 +0100 [thread overview]
Message-ID: <aLWDt9NpfYO_Utky@arm.com> (raw)
In-Reply-To: <20250829080735.3598416-2-ankur.a.arora@oracle.com>
On Fri, Aug 29, 2025 at 01:07:31AM -0700, Ankur Arora wrote:
> Add smp_cond_load_relaxed_timewait(), which extends
> smp_cond_load_relaxed() to allow waiting for a finite duration.
>
> The additional parameter allows for the timeout check.
>
> The waiting is done via the usual cpu_relax() spin-wait around the
> condition variable with periodic evaluation of the time-check.
>
> The number of times we spin is defined by SMP_TIMEWAIT_SPIN_COUNT
> (chosen to be 200 by default) which, assuming each cpu_relax()
> iteration takes around 20-30 cycles (measured on a variety of x86
> platforms), amounts to around 4000-6000 cycles.
>
> Cc: Arnd Bergmann <arnd@arndb.de>
> Cc: Will Deacon <will@kernel.org>
> Cc: Catalin Marinas <catalin.marinas@arm.com>
> Cc: Peter Zijlstra <peterz@infradead.org>
> Cc: linux-arch@vger.kernel.org
> Signed-off-by: Ankur Arora <ankur.a.arora@oracle.com>
Apart from the name, this looks fine (I'd have preferred the "timeout"
suffix).
Reviewed-by: Catalin Marinas <catalin.marinas@arm.com>
next prev parent reply other threads:[~2025-09-01 11:30 UTC|newest]
Thread overview: 23+ messages / expand[flat|nested] mbox.gz Atom feed top
2025-08-29 8:07 [PATCH v4 0/5] barrier: Add smp_cond_load_*_timewait() Ankur Arora
2025-08-29 8:07 ` [PATCH v4 1/5] asm-generic: barrier: Add smp_cond_load_relaxed_timewait() Ankur Arora
2025-09-01 11:29 ` Catalin Marinas [this message]
2025-09-02 21:34 ` Ankur Arora
2025-08-29 8:07 ` [PATCH v4 2/5] arm64: " Ankur Arora
2025-09-01 11:47 ` Catalin Marinas
2025-09-02 22:40 ` Ankur Arora
2025-08-29 8:07 ` [PATCH v4 3/5] arm64: rqspinlock: Remove private copy of smp_cond_load_acquire_timewait Ankur Arora
2025-09-01 11:47 ` Catalin Marinas
2025-08-29 8:07 ` [PATCH v4 4/5] asm-generic: barrier: Add smp_cond_load_acquire_timewait() Ankur Arora
2025-09-01 11:47 ` Catalin Marinas
2025-08-29 8:07 ` [PATCH v4 5/5] rqspinlock: use smp_cond_load_acquire_timewait() Ankur Arora
2025-09-01 11:28 ` Catalin Marinas
2025-09-02 17:43 ` Alexei Starovoitov
2025-09-02 21:30 ` Ankur Arora
2025-09-02 21:31 ` Ankur Arora
2025-08-29 18:54 ` [PATCH v4 0/5] barrier: Add smp_cond_load_*_timewait() Okanovic, Haris
2025-08-29 22:38 ` Ankur Arora
2025-09-01 11:49 ` Catalin Marinas
2025-09-02 22:46 ` Ankur Arora
2025-09-03 9:27 ` Catalin Marinas
2025-09-03 18:34 ` Ankur Arora
2025-09-03 15:56 ` Okanovic, Haris
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