Hi Beata,
On Tuesday 12 Mar 2024 at 08:34:28 (+0000), 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.
Relevant discussions:
[1] https://lore.kernel.org/all/20240229162520.970986-1-vanshikonda@xxxxxxxxxxxxxxxxxxxxxx/
[2] https://lore.kernel.org/all/7eozim2xnepacnnkzxlbx34hib4otycnbn4dqymfziqou5lw5u@5xzpv3t7sxo3/
[3] https://lore.kernel.org/all/20231212072617.14756-1-lihuisong@xxxxxxxxxx/
[4] https://lore.kernel.org/lkml/ZIHpd6unkOtYVEqP@xxxxxxxxxxxxxxxxxxxxxxxxx/T/#m4e74cb5a0aaa353c60fedc6cfb95ab7a6e381e3c
v3:
- dropping changes to cpufreq_verify_current_freq
- pulling in changes from Ionela initializing capacity_freq_ref to 0
(thanks for that!) and applying suggestions made by her during last review:
- switching to arch_scale_freq_capacity and arch_scale_freq_ref when
reversing freq scale factor computation
- swapping shift with multiplication
- adding time limit for considering last scale update as valid
- updating frequency scale factor upon entering idle
v2:
- Splitting the patches
- Adding comment for full dyntick mode
- Plugging arch_freq_get_on_cpu into cpufreq_verify_current_freq instead
of in show_cpuinfo_cur_freq to allow the framework to stay more in sync
with potential freq changes
Beata Michalska (2):
arm64: Provide an AMU-based version of arch_freq_get_on_cpu
arm64: Update AMU-based frequency scale factor on entering idle
Ionela Voinescu (1):
arch_topology: init capacity_freq_ref to 0
Should there have been a patch that adds a call to
arch_freq_get_on_cpu() from show_cpuinfo_cur_freq() as well?
My understanding from this [1] thread and others referenced there is
that was something we wanted.
Right, so I must have missunderstood that, as the way I did read it was that
it is acceptable to keep things as they are wrt cpufreq sysfs entries.
---
BR
Beata
[1] https://lore.kernel.org/lkml/2cfbc633-1e94-d741-2337-e1b0cf48b81b@xxxxxxxxxx/
Thanks,
Ionela.
Yes, the change to show_cpuinfo_cur_freq from [1] is needed.
[1]
https://lore.kernel.org/lkml/20230606155754.245998-1-beata.michalska@xxxxxxx/
Thank you,
Sumit Gupta
