From: Viresh Kumar <viresh.kumar@linaro.org>
To: Dietmar Eggemann <dietmar.eggemann@arm.com>
Cc: linux-kernel@vger.kernel.org, linux-pm@vger.kernel.org,
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: Thu, 6 Jul 2017 16:10:27 +0530 [thread overview]
Message-ID: <20170706104027.GB13048@vireshk-i7> (raw)
In-Reply-To: <20170706094948.8779-3-dietmar.eggemann@arm.com>
On 06-07-17, 10:49, Dietmar Eggemann wrote:
> A frequency-invariant load-tracking solution based on cpufreq transition
> notifier will not work for future fast frequency switching policies.
> That is why a different solution is presented with this patch.
>
> Let cpufreq call the function arch_set_freq_scale() to pass the current
> frequency, the max supported frequency and the cpumask of the related
> cpus to a consumer (an arch) which defines arch_set_freq_scale().
>
> The consumer has to associate arch_set_freq_scale with the name of its
> own implementation foo_set_freq_scale() to overwrite the empty standard
> definition in drivers/cpufreq/cpufreq.c.
> An arch could do this in one of its arch-specific header files
> (e.g. arch/$ARCH/include/asm/topology.h) which gets included in
> drivers/cpufreq/cpufreq.c.
>
> 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.
> the
> function cpufreq_set_freq_scale() gets compiled out.
>
> Cc: Rafael J. Wysocki <rjw@rjwysocki.net>
> Cc: Viresh Kumar <viresh.kumar@linaro.org>
> Signed-off-by: Dietmar Eggemann <dietmar.eggemann@arm.com>
> ---
> drivers/cpufreq/cpufreq.c | 26 ++++++++++++++++++++++++++
> 1 file changed, 26 insertions(+)
>
> 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.
> +}
> +
> /**
> * 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..
> 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.
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.
--
viresh
next prev parent reply other threads:[~2017-07-06 10:40 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 [this message]
2017-07-06 22:38 ` Rafael J. Wysocki
2017-07-07 16:01 ` Dietmar Eggemann
2017-07-07 16:18 ` Rafael J. Wysocki
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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