From: Keyon Jie <yang.jie@linux.intel.com>
To: "Rafael J. Wysocki" <rafael@kernel.org>
Cc: Greg KH <gregkh@linuxfoundation.org>,
Doug Smythies <dsmythies@telus.net>,
Srinivas Pandruvada <srinivas.pandruvada@linux.intel.com>,
Len Brown <lenb@kernel.org>, Thomas Gleixner <tglx@linutronix.de>,
Linux PM <linux-pm@vger.kernel.org>,
LKML <linux-kernel@vger.kernel.org>
Subject: Re: [PATCH v2] cpufreq: intel_pstate: set stale CPU frequency to minimum
Date: Tue, 5 Sep 2023 15:23:41 -0700 [thread overview]
Message-ID: <3b798806-d144-58a8-6fa3-e893299bc690@linux.intel.com> (raw)
In-Reply-To: <CAJZ5v0i4_PnCJGkkMzBMF9GX3N6LLNQdnuyX6nRzWHy_f9T=3A@mail.gmail.com>
On 9/5/23 11:30, Rafael J. Wysocki wrote:
> On Tue, Sep 5, 2023 at 8:17 PM Keyon Jie <yang.jie@linux.intel.com> wrote:
>>
>>
>>
>> On 8/29/23 01:57, Greg KH wrote:
>>> On Mon, Aug 28, 2023 at 04:35:13PM -0700, Keyon Jie wrote:
>>>>
>>>>
>>>> On 8/22/23 04:46, Rafael J. Wysocki wrote:
>>>>> On Sun, Aug 20, 2023 at 10:46 PM Doug Smythies <dsmythies@telus.net> wrote:
>>>>>>
>>>>>> The intel_pstate CPU frequency scaling driver does not
>>>>>> use policy->cur and it is 0.
>>>>>> When the CPU frequency is outdated arch_freq_get_on_cpu()
>>>>>> will default to the nominal clock frequency when its call to
>>>>>> cpufreq_quick_getpolicy_cur returns the never updated 0.
>>>>>> Thus, the listed frequency might be outside of currently
>>>>>> set limits. Some users are complaining about the high
>>>>>> reported frequency, albeit stale, when their system is
>>>>>> idle and/or it is above the reduced maximum they have set.
>>>>>>
>>>>>> This patch will maintain policy_cur for the intel_pstate
>>>>>> driver at the current minimum CPU frequency.
>>>>>>
>>>>>> Reported-by: Yang Jie <yang.jie@linux.intel.com>
>>>>>> Closes: https://bugzilla.kernel.org/show_bug.cgi?id=217597
>>>>>> Signed-off-by: Doug Smythies <dsmythies@telus.net>
>>>>>> ---
>>>>>>
>>>>>> v1 -> v2:
>>>>>> * v1 was a completely different approach, programming around
>>>>>> the issue rather than fixing it at the source.
>>>>>> reference:
>>>>>> https://patchwork.kernel.org/project/linux-pm/patch/006901d9be8c$f4439930$dccacb90$@telus.net/
>>>>>> * v2 does not fix an issue with the intel_cpufreq CPU scaling
>>>>>> driver (A.K.A. the intel_pstate driver in passive mode) and
>>>>>> the schedutil CPU frequency scaling governor when HWP is enabled
>>>>>> where limit changes are not reflected in the stale listed frequencies.
>>>>>> A fix for that will be some future patch.
>>>>>>
>>>>>> ---
>>>>>> drivers/cpufreq/intel_pstate.c | 5 +++++
>>>>>> 1 file changed, 5 insertions(+)
>>>>>>
>>>>>> diff --git a/drivers/cpufreq/intel_pstate.c b/drivers/cpufreq/intel_pstate.c
>>>>>> index 8ca2bce4341a..08284dee583a 100644
>>>>>> --- a/drivers/cpufreq/intel_pstate.c
>>>>>> +++ b/drivers/cpufreq/intel_pstate.c
>>>>>> @@ -2609,6 +2609,11 @@ static int intel_pstate_set_policy(struct cpufreq_policy *policy)
>>>>>> intel_pstate_clear_update_util_hook(policy->cpu);
>>>>>> intel_pstate_hwp_set(policy->cpu);
>>>>>> }
>>>>>> + /* policy current is never updated with the intel_pstate driver
>>>>>> + * but it is used as a stale frequency value. So, keep it within
>>>>>> + * limits.
>>>>>> + */
>>>>>> + policy->cur = policy->min;
>>>>>>
>>>>>> mutex_unlock(&intel_pstate_limits_lock);
>>>>>>
>>>>>> --
>>>>>
>>>>> Applied as 6.6 material, with some mailer-induced white space damage
>>>>> fixed and the new comment adjusted to the kernel coding style.
>>>>>
>>>>> Thanks!
>>>>
>>>> Hi Doug and Rafael,
>>>>
>>>> Thank you for making the fix happen.
>>>>
>>>> Hi Greg,
>>>>
>>>> Will this be picked to the stable linux-6.1.y and linux-6.4.y kernel, it
>>>> could benefit to users there.
>>>
>>> Sure, when it hits Linus's tree, please follow the instructions in:
>>> https://www.kernel.org/doc/html/latest/process/stable-kernel-rules.html
>>> for how to get it merged.
>>
>> Thank you Greg.
>>
>> Hi Rafael,
>>
>> As the issue happens from the 5.18 onward kernels, we need the fix to be
>> picked for stable kernels after that, could you please help to add "Cc:
>> stable@vger.kernel.org" in the sign-off area when you send it to the
>> mainline?
>
> It's already merged, as commit d51847acb018 ("cpufreq: intel_pstate:
> set stale CPU frequency to minimum").
>
> Please feel free to send an inclusion request for it to stable@vger.kernel.org
Thank you Rafael, will do.
Thanks,
~Keyon
>
> Thanks!
prev parent reply other threads:[~2023-09-05 22:23 UTC|newest]
Thread overview: 7+ messages / expand[flat|nested] mbox.gz Atom feed top
2023-08-20 20:46 [PATCH v2] cpufreq: intel_pstate: set stale CPU frequency to minimum Doug Smythies
2023-08-22 11:46 ` Rafael J. Wysocki
2023-08-28 23:35 ` Keyon Jie
2023-08-29 8:57 ` Greg KH
2023-09-05 18:17 ` Keyon Jie
2023-09-05 18:30 ` Rafael J. Wysocki
2023-09-05 22:23 ` Keyon Jie [this message]
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