Re: [PATCH v6 0/4] Add support for AArch64 AMUv1-based arch_freq_get_on_cpu

[Beata Michalska]

Hi Catalin,

On Mon, Jul 08, 2024 at 06:10:02PM +0100, Catalin Marinas wrote:
> Hi Beata,
> 
> On Mon, Jun 03, 2024 at 09:21:50AM +0100, Beata Michalska wrote:
> > Introducing arm64 specific version of arch_freq_get_on_cpu, cashing on
> > existing implementation for FIE and AMUv1 support: the frequency scale
> > factor, updated on each sched tick, serves as a base for retrieving
> > the frequency for a given CPU, representing an average frequency
> > reported between the ticks - thus its accuracy is limited.
> > 
> > The changes have been rather lightly (due to some limitations) tested on
> > an FVP model. Note that some small discrepancies have been observed while
> > testing (on the model) and this is currently being investigated, though it
> > should not have any significant impact on the overall results.
> 
> What's the plan with this series? Are you still investigating those
> discrepancies or is it good to go?
>
Overall it should be good to go with small caveat:
as per discussion [1] we might need to provide new sysfs attribute exposing an
average frequency instead of plugging new code under existing cpuinfo_cur_freq.
This is to avoid messing up with other archs and make a clean distinction on
which attribute provides what information. 
As such, the arch_freq_get_on_cpu implementation provided within this series
[PATCH v6 3/4] will most probably be shifted to a new function.

Hopefully will be able to send those changes soon.

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[1] https://lore.kernel.org/all/ZmrB_DqtmVpvG30l@xxxxxxx/
---
BR
Beata

> -- 
> Catalin