From: Greg KH <gregkh@linuxfoundation.org>
To: Keyon Jie <yang.jie@linux.intel.com>
Cc: "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, 29 Aug 2023 10:57:32 +0200 [thread overview]
Message-ID: <2023082901-moonscape-album-b7cc@gregkh> (raw)
In-Reply-To: <9665af79-d439-e05a-5333-62f71a2ac55c@linux.intel.com>
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 When the CPU frequency is outdated arch_freq_get_on_cpu()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.
thanks,
greg k-h
next prev parent reply other threads:[~2023-08-29 8:58 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 [this message]
2023-09-05 18:17 ` Keyon Jie
2023-09-05 18:30 ` Rafael J. Wysocki
2023-09-05 22:23 ` Keyon Jie
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