From: "Rafael J. Wysocki" <rafael@kernel.org>
To: Keyon Jie <yang.jie@linux.intel.com>
Cc: Greg KH <gregkh@linuxfoundation.org>,
"Rafael J. Wysocki" <rafael@kernel.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 20:30:34 +0200 [thread overview]
Message-ID: <CAJZ5v0i4_PnCJGkkMzBMF9GX3N6LLNQdnuyX6nRzWHy_f9T=3A@mail.gmail.com> (raw)
In-Reply-To: <02d8a574-a07a-f595-aee2-13908df74e68@linux.intel.com>
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 When the CPU frequency is outdated arch_freq_get_on_cpu()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
Thanks!
next prev parent reply other threads:[~2023-09-05 18:32 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 [this message]
2023-09-05 22:23 ` Keyon Jie
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