From: "Rafael J. Wysocki" <rafael@kernel.org>
To: Dietmar Eggemann <dietmar.eggemann@arm.com>
Cc: Viresh Kumar <viresh.kumar@linaro.org>,
Linux Kernel Mailing List <linux-kernel@vger.kernel.org>,
Linux PM <linux-pm@vger.kernel.org>,
Russell King - ARM Linux <linux@arm.linux.org.uk>,
Greg Kroah-Hartman <gregkh@linuxfoundation.org>,
Russell King <rmk+kernel@armlinux.org.uk>,
Catalin Marinas <catalin.marinas@arm.com>,
Will Deacon <will.deacon@arm.com>,
Juri Lelli <juri.lelli@arm.com>,
Vincent Guittot <vincent.guittot@linaro.org>,
Peter Zijlstra <peterz@infradead.org>,
Morten Rasmussen <morten.rasmussen@arm.com>,
"Rafael J . Wysocki" <rjw@rjwysocki.net>
Subject: Re: [PATCH v2 02/10] cpufreq: provide data for frequency-invariant load-tracking support
Date: Fri, 7 Jul 2017 18:18:15 +0200 [thread overview]
Message-ID: <CAJZ5v0gBPNDBYWbuHVaB7deNHSZKziaAeybSw3mg+S8V_roO-Q@mail.gmail.com> (raw)
In-Reply-To: <c92f1bd0-6611-8eec-51d7-f6d7754a5870@arm.com>
On Fri, Jul 7, 2017 at 6:01 PM, Dietmar Eggemann
<dietmar.eggemann@arm.com> wrote:
> On 06/07/17 11:40, Viresh Kumar wrote:
>> On 06-07-17, 10:49, Dietmar Eggemann wrote:
>
> [...]
>
>>> In case arch_set_freq_scale() is not defined (and because of the
>>> pr_debug() drivers/cpufreq/cpufreq.c is not compiled with -DDEBUG)
>>
>> The line within () needs to be improved to convey a clear message.
>
> Probably not needed anymore. See below.
>
> [...]
>
>>> diff --git a/drivers/cpufreq/cpufreq.c b/drivers/cpufreq/cpufreq.c
>>> index 9bf97a366029..a04c5886a5ce 100644
>>> --- a/drivers/cpufreq/cpufreq.c
>>> +++ b/drivers/cpufreq/cpufreq.c
>>> @@ -347,6 +347,28 @@ static void __cpufreq_notify_transition(struct cpufreq_policy *policy,
>>> }
>>> }
>>>
>>> +/*********************************************************************
>>> + * FREQUENCY INVARIANT CPU CAPACITY SUPPORT *
>>> + *********************************************************************/
>>> +
>>> +#ifndef arch_set_freq_scale
>>> +static void arch_set_freq_scale(struct cpumask *cpus, unsigned long cur_freq,
>>> + unsigned long max_freq)
>>> +{}
>>> +#endif
>>> +
>>> +static void cpufreq_set_freq_scale(struct cpufreq_policy *policy,
>>> + struct cpufreq_freqs *freqs)
>>> +{
>>> + unsigned long cur_freq = freqs ? freqs->new : policy->cur;
>>> + unsigned long max_freq = policy->cpuinfo.max_freq;
>>> +
>>> + pr_debug("cpus %*pbl cur/cur max freq %lu/%lu kHz\n",
>>> + cpumask_pr_args(policy->related_cpus), cur_freq, max_freq);
>>> +
>>> + arch_set_freq_scale(policy->related_cpus, cur_freq, max_freq);
>>
>> I am not sure why all these are required to be sent here and will come back to
>> it later on after going through other patches.
>
> See below.
>
>>> +}
>>> +
>>> /**
>>> * cpufreq_notify_transition - call notifier chain and adjust_jiffies
>>> * on frequency transition.
>>> @@ -405,6 +427,8 @@ void cpufreq_freq_transition_begin(struct cpufreq_policy *policy,
>>>
>>> spin_unlock(&policy->transition_lock);
>>>
>>> + cpufreq_set_freq_scale(policy, freqs);
>>> +
>>
>> Why do this before even changing the frequency ? We may fail while changing it.
>>
>> IMHO, you should call this routine whenever we update policy->cur and that
>> happens regularly in __cpufreq_notify_transition() and few other places..
>
> See below.
>
>>> cpufreq_notify_transition(policy, freqs, CPUFREQ_PRECHANGE);
>>> }
>>> EXPORT_SYMBOL_GPL(cpufreq_freq_transition_begin);
>>> @@ -2203,6 +2227,8 @@ static int cpufreq_set_policy(struct cpufreq_policy *policy,
>>> blocking_notifier_call_chain(&cpufreq_policy_notifier_list,
>>> CPUFREQ_NOTIFY, new_policy);
>>>
>>> + cpufreq_set_freq_scale(new_policy, NULL);
>>
>> Why added it here ? To get it initialized ? If yes, then we should do that in
>> cpufreq_online() where we first initialize policy->cur.
>
> I agree. This can go away. Initialization is not really needed here. We initialize
> the scale values to SCHED_CAPACITY_SCALE at boot-time.
>
>> Apart from this, you also need to update this in the schedutil governor (if you
>> haven't done that in this series later) as that also updates policy->cur in the
>> fast path.
>
> So what about I call arch_set_freq_scale() in __cpufreq_notify_transition() in the
> CPUFREQ_POSTCHANGE case for slow-switching and in cpufreq_driver_fast_switch() for
> fast-switching?
Why don't you do this in drivers instead of in the core?
Ultimately, the driver knows what frequency it has requested, so why
can't it call arch_set_freq_scale()?
Thanks,
Rafael
next prev parent reply other threads:[~2017-07-07 16:19 UTC|newest]
Thread overview: 62+ messages / expand[flat|nested] mbox.gz Atom feed top
2017-07-06 9:49 [PATCH v2 00/10] arm, arm64: frequency- and cpu-invariant accounting support for task scheduler Dietmar Eggemann
2017-07-06 9:49 ` [PATCH v2 01/10] drivers base/arch_topology: free cpumask cpus_to_visit Dietmar Eggemann
2017-07-06 10:22 ` Viresh Kumar
2017-07-06 10:59 ` Juri Lelli
2017-07-06 11:15 ` Viresh Kumar
2017-07-07 15:50 ` Dietmar Eggemann
2017-07-06 9:49 ` [PATCH v2 02/10] cpufreq: provide data for frequency-invariant load-tracking support Dietmar Eggemann
2017-07-06 10:40 ` Viresh Kumar
2017-07-06 22:38 ` Rafael J. Wysocki
2017-07-07 16:01 ` Dietmar Eggemann
2017-07-07 16:18 ` Rafael J. Wysocki [this message]
2017-07-07 17:06 ` Dietmar Eggemann
2017-07-08 12:09 ` Rafael J. Wysocki
2017-07-10 6:54 ` Viresh Kumar
2017-07-10 12:46 ` Rafael J. Wysocki
2017-07-11 6:39 ` Viresh Kumar
2017-07-11 15:21 ` Dietmar Eggemann
2017-07-13 12:40 ` Sudeep Holla
2017-07-13 13:08 ` Dietmar Eggemann
2017-07-13 14:06 ` Sudeep Holla
2017-07-10 9:30 ` Peter Zijlstra
2017-07-10 9:42 ` Viresh Kumar
2017-07-10 10:31 ` Dietmar Eggemann
2017-07-10 12:02 ` Dietmar Eggemann
2017-07-11 6:01 ` Viresh Kumar
2017-07-11 15:06 ` Dietmar Eggemann
2017-07-11 14:59 ` Rafael J. Wysocki
2017-07-11 15:12 ` Dietmar Eggemann
2017-07-12 4:09 ` Viresh Kumar
2017-07-12 8:31 ` Peter Zijlstra
2017-07-12 9:27 ` Viresh Kumar
2017-07-12 11:14 ` Peter Zijlstra
2017-07-12 23:13 ` Rafael J. Wysocki
2017-07-13 7:49 ` Peter Zijlstra
2017-07-13 8:48 ` Viresh Kumar
2017-07-13 11:15 ` Peter Zijlstra
2017-07-13 14:04 ` Sudeep Holla
2017-07-13 14:42 ` Peter Zijlstra
2017-07-13 15:00 ` Sudeep Holla
2017-07-13 12:54 ` Sudeep Holla
2017-07-13 12:49 ` Sudeep Holla
2017-07-10 6:40 ` Viresh Kumar
2017-07-06 9:49 ` [PATCH v2 03/10] drivers base/arch_topology: " Dietmar Eggemann
2017-07-06 10:45 ` Viresh Kumar
2017-07-07 16:51 ` Dietmar Eggemann
2017-07-06 9:49 ` [PATCH v2 04/10] arm: wire cpufreq input data for frequency-invariant accounting up to the arch Dietmar Eggemann
2017-07-06 10:42 ` Viresh Kumar
2017-07-10 15:13 ` Dietmar Eggemann
2017-07-11 6:32 ` Viresh Kumar
2017-07-06 9:49 ` [PATCH v2 05/10] arm: wire frequency-invariant accounting support up to the task scheduler Dietmar Eggemann
2017-07-06 10:46 ` Viresh Kumar
2017-07-06 9:49 ` [PATCH v2 06/10] arm: wire cpu-invariant " Dietmar Eggemann
2017-07-06 10:47 ` Viresh Kumar
2017-07-06 9:49 ` [PATCH v2 07/10] arm64: wire cpufreq input data for frequency-invariant accounting up to the arch Dietmar Eggemann
2017-07-06 10:48 ` Viresh Kumar
2017-07-06 9:49 ` [PATCH v2 08/10] arm64: wire frequency-invariant accounting support up to the task scheduler Dietmar Eggemann
2017-07-06 10:48 ` Viresh Kumar
2017-07-06 9:49 ` [PATCH v2 09/10] arm64: wire cpu-invariant " Dietmar Eggemann
2017-07-06 10:49 ` Viresh Kumar
2017-07-06 9:49 ` [PATCH v2 10/10] drivers base/arch_topology: inline cpu- and frequency-invariant accounting Dietmar Eggemann
2017-07-06 10:57 ` Viresh Kumar
2017-07-10 15:17 ` Dietmar Eggemann
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