From: Andrew Morton <akpm@linux-foundation.org>
To: Yicong Yang <yangyicong@huawei.com>
Cc: <catalin.marinas@arm.com>, <will@kernel.org>,
<dianders@chromium.org>, <sumit.garg@linaro.org>,
<kernelfans@gmail.com>, <lecopzer.chen@mediatek.com>,
<tglx@linutronix.de>, <song@kernel.org>,
<linux-arm-kernel@lists.infradead.org>,
<jonathan.cameron@huawei.com>, <zhanjie9@hisilicon.com>,
<prime.zeng@hisilicon.com>, <yangyicong@hisilicon.com>,
<linuxarm@huawei.com>
Subject: Re: [PATCH v2 0/2] Update the watchdog period according to real CPU frequency
Date: Mon, 12 May 2025 16:06:12 -0700 [thread overview]
Message-ID: <20250512160612.c10464075df3c7842b13da11@linux-foundation.org> (raw)
In-Reply-To: <20250512130919.23915-1-yangyicong@huawei.com>
On Mon, 12 May 2025 21:09:17 +0800 Yicong Yang <yangyicong@huawei.com> wrote:
> From: Yicong Yang <yangyicong@hisilicon.com>
>
> watchdog perf needs architecture to provide method for converting the watchdog
> thresh to counter period. For arm64 we're using the max CPU frequency for
> doing the conversion which is from cpufreq driver. But some cpufreq driver
> are registered lately, for example cppc_cpufreq will be registered at late
> initcall which is after the initialization of watchdog perf (initialized in
> armv8_pmuv3 of device initcall). In such case the period of watchdog will not
> be accurate enough. Fix this by registering a cpufreq notifier and update the
> watchdog period once the cpufreq driver is initialized.
>
Thanks. Thoughts.
1: What is the impact of this change? Is the current code causing
problems? If so, what are they? How is the end-user experience
improved by this change? Important info!
2: As far as I can tell, this patchset impacts arm64 only. Do you
think that other architectures should implement this?
3: As far as I can tell, this patchset affects all cpufreq drivers
which use late_initcall() (on arm64, of course). Is this correct?
4: It is asserted that we should use the *maximum* possible CPU
frequency for this calculation. Why? I assume this is because we
care about the minimum watchdog period?
Can I assume that the ARM maintainers will be handling this?
next prev parent reply other threads:[~2025-05-12 23:08 UTC|newest]
Thread overview: 9+ messages / expand[flat|nested] mbox.gz Atom feed top
2025-05-12 13:09 [PATCH v2 0/2] Update the watchdog period according to real CPU frequency Yicong Yang
2025-05-12 13:09 ` [PATCH v2 1/2] watchdog/perf: Provide function for adjusting the event period Yicong Yang
2025-05-12 23:07 ` Andrew Morton
2025-05-13 7:02 ` Yicong Yang
2025-05-12 13:09 ` [PATCH v2 2/2] arm64/watchdog_hld: Add a cpufreq notifier for update watchdog thresh Yicong Yang
2025-05-12 23:06 ` Andrew Morton [this message]
2025-05-13 6:51 ` [PATCH v2 0/2] Update the watchdog period according to real CPU frequency Yicong Yang
2025-06-27 15:26 ` Will Deacon
2025-06-27 18:56 ` Andrew Morton
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