From: "Arnd Bergmann" <arnd@arndb.de>
To: "Catalin Marinas" <catalin.marinas@arm.com>,
"Ankur Arora" <ankur.a.arora@oracle.com>
Cc: linux-kernel@vger.kernel.org,
Linux-Arch <linux-arch@vger.kernel.org>,
linux-arm-kernel@lists.infradead.org, bpf@vger.kernel.org,
"Will Deacon" <will@kernel.org>,
"Peter Zijlstra" <peterz@infradead.org>,
"Andrew Morton" <akpm@linux-foundation.org>,
"Mark Rutland" <mark.rutland@arm.com>,
harisokn@amazon.com, cl@gentwo.org,
"Alexei Starovoitov" <ast@kernel.org>,
"Kumar Kartikeya Dwivedi" <memxor@gmail.com>,
zhenglifeng1@huawei.com, xueshuai@linux.alibaba.com,
"Joao Martins" <joao.m.martins@oracle.com>,
"Boris Ostrovsky" <boris.ostrovsky@oracle.com>,
"Konrad Rzeszutek Wilk" <konrad.wilk@oracle.com>,
"Rafael J . Wysocki" <rafael@kernel.org>,
"Daniel Lezcano" <daniel.lezcano@linaro.org>
Subject: Re: [PATCH v3 1/5] asm-generic: barrier: Add smp_cond_load_relaxed_timewait()
Date: Wed, 13 Aug 2025 18:29:37 +0200 [thread overview]
Message-ID: <67b6b738-0f1c-4dd4-817d-95f55ec9272b@app.fastmail.com> (raw)
In-Reply-To: <aJy414YufthzC1nv@arm.com>
On Wed, Aug 13, 2025, at 18:09, Catalin Marinas wrote:
> On Mon, Aug 11, 2025 at 02:15:56PM -0700, Ankur Arora wrote:
>
>> This also gives the WFET a clear end time (though it would still need
>> to be converted to timer cycles) but the WFE path could stay simple
>> by allowing an overshoot instead of falling back to polling.
>
> For arm64, both WFE and WFET would be woken up by the event stream
> (which is enabled on all production systems). The only reason to use
> WFET is if you need smaller granularity than the event stream period
> (100us). In this case, we should probably also add a fallback from WFE
> to a busy loop.
I think there is a reasonable chance that in the future we may want
to turn the event stream off on systems that support WFET, since that
is better for both low-power systems and virtual machines with CPU
overcommit.
Arnd
next prev parent reply other threads:[~2025-08-13 17:07 UTC|newest]
Thread overview: 26+ messages / expand[flat|nested] mbox.gz Atom feed top
2025-06-27 4:48 [PATCH v3 0/5] barrier: Add smp_cond_load_*_timewait() Ankur Arora
2025-06-27 4:48 ` [PATCH v3 1/5] asm-generic: barrier: Add smp_cond_load_relaxed_timewait() Ankur Arora
2025-08-08 10:51 ` Catalin Marinas
2025-08-11 21:15 ` Ankur Arora
2025-08-13 16:09 ` Catalin Marinas
2025-08-13 16:29 ` Arnd Bergmann [this message]
2025-08-13 16:54 ` Christoph Lameter (Ampere)
2025-08-14 13:00 ` Catalin Marinas
2025-08-18 11:51 ` Arnd Bergmann
2025-08-18 18:28 ` Catalin Marinas
2025-08-14 7:30 ` Ankur Arora
2025-08-14 11:39 ` Catalin Marinas
2025-08-17 22:14 ` Ankur Arora
2025-08-18 17:55 ` Catalin Marinas
2025-08-18 19:15 ` Ankur Arora
2025-08-19 10:34 ` Catalin Marinas
2025-06-27 4:48 ` [PATCH v3 2/5] asm-generic: barrier: Handle spin-wait in smp_cond_load_relaxed_timewait() Ankur Arora
2025-06-27 4:48 ` [PATCH v3 3/5] asm-generic: barrier: Add smp_cond_load_acquire_timewait() Ankur Arora
2025-08-08 9:38 ` Catalin Marinas
2025-08-12 5:18 ` Ankur Arora
2025-06-27 4:48 ` [PATCH v3 4/5] arm64: barrier: Support waiting in smp_cond_load_relaxed_timewait() Ankur Arora
2025-06-27 4:48 ` [PATCH v3 5/5] arm64: barrier: Handle " Ankur Arora
2025-06-30 16:33 ` Christoph Lameter (Ampere)
2025-06-30 21:05 ` Ankur Arora
2025-07-01 5:55 ` Ankur Arora
2025-07-28 19:03 ` [PATCH v3 0/5] barrier: Add smp_cond_load_*_timewait() Ankur Arora
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