Re: [PATCH v6 1/4] cpufreq: Remove per-CPU QoS constraint

[Pierre Gondois <pierre.gondois@arm.com>]

On 3/18/26 12:13, Viresh Kumar wrote:
> On 17-03-26, 11:17, Pierre Gondois wrote:
>> policy->max_freq_req represents the maximum allowed frequency as
>> requested by the policyX/scaling_max_freq sysfs file. This request
>> applies to all CPUs of the policy. It is not possible to request
>> a per-CPU maximum frequency.
>>
>> Thus, the interaction between the policy boost and scaling_max_freq
>> settings should be handled by adding a boost specific QoS constraint.
>> This will be handled in the following patches.
> I don't think the above is required anymore. This patch is removing stale code
> now which isn't useful anymore. It has nothing to do with a boost specific QOS
> constraint.
Yes ok
> And it would be better to know for sure why this isn't required anymore and
> which patch exactly fixed this issue.
>
On a kernel based on 1608f0230510~, and replicating the
process described in the commit message of

commit 1608f0230510 ("cpufreq: Fix re-boost issue after hotplugging
a CPU")

I could not see any issue regarding the values of:

- policy1/cpuinfo_max_freq
- policy1/scaling_max_freq

The following sequence however had an issue:

1. echo 0 > /sys/devices/system/cpu/cpu1/online
2. echo 1 > /sys/devices/system/cpu/cpufreq/boost
3. echo 1 > /sys/devices/system/cpu/cpu1/online

as after 1.:

cpufreq_boost_trigger_state()
\-for_each_active_policy()

doesn't enable boost for inactive policies. This leads to
CPU1 having the non-boosted frequency as its max freq.

The above sequence is fixed by:

commit a153c6049ab8 ("cpufreq: Introduce a more
generic way to set default per-policy boost flag")

---

@Lifeng, should I check something else than the value of:

- policy1/cpuinfo_max_freq
- policy1/scaling_max_freq

in order to reproduce the issue fixed by:

commit 1608f0230510 ("cpufreq: Fix re-boost issue after hotplugging
a CPU")

?