[PATCH v2 0/2] Update the watchdog period according to real CPU frequency

[Andrew Morton]

On Mon, 12 May 2025 21:09:17 +0800 Yicong Yang <yangyicong at huawei.com> wrote:

> From: Yicong Yang <yangyicong at 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?