Date: Wed, 16 Mar 2016 19:14:20 +0100
From: Peter Zijlstra <peterz@infradead.org>
To: "Rafael J. Wysocki" <rjw@rjwysocki.net>
Cc: Linux PM list <linux-pm@vger.kernel.org>, Juri Lelli <juri.lelli@arm.com>,
        Steve Muckle <steve.muckle@linaro.org>,
        ACPI Devel Maling List <linux-acpi@vger.kernel.org>,
        Linux Kernel Mailing List <linux-kernel@vger.kernel.org>,
        Srinivas Pandruvada <srinivas.pandruvada@linux.intel.com>,
        Viresh Kumar <viresh.kumar@linaro.org>,
        Vincent Guittot <vincent.guittot@linaro.org>,
        Michael Turquette <mturquette@baylibre.com>,
        Ingo Molnar <mingo@kernel.org>
Subject: Re: [PATCH v4 7/7] cpufreq: schedutil: New governor based on
 scheduler utilization data
Message-ID: <20160316181420.GH6344@twins.programming.kicks-ass.net>
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On Wed, Mar 16, 2016 at 03:59:18PM +0100, Rafael J. Wysocki wrote:
> +static void sugov_update_commit(struct sugov_policy *sg_policy, u64 time,
> +				unsigned int next_freq)
> +{
> +	struct cpufreq_policy *policy = sg_policy->policy;
> +
> +	if (next_freq > policy->max)
> +		next_freq = policy->max;
> +	else if (next_freq < policy->min)
> +		next_freq = policy->min;
> +
> +	sg_policy->last_freq_update_time = time;
> +	if (sg_policy->next_freq == next_freq) {
> +		if (policy->fast_switch_enabled)
> +			trace_cpu_frequency(policy->cur, smp_processor_id());
> +
> +		return;
> +	}
> +
> +	sg_policy->next_freq = next_freq;
> +	if (policy->fast_switch_enabled) {
> +		unsigned int freq;
> +
> +		freq = cpufreq_driver_fast_switch(policy, next_freq);

So you're assuming a RELATION_L for ->fast_switch() ?

> +		if (freq == CPUFREQ_ENTRY_INVALID)
> +			return;
> +
> +		policy->cur = freq;
> +		trace_cpu_frequency(freq, smp_processor_id());
> +	} else {
> +		sg_policy->work_in_progress = true;
> +		irq_work_queue(&sg_policy->irq_work);
> +	}
> +}


> +static void sugov_work(struct work_struct *work)
> +{
> +	struct sugov_policy *sg_policy = container_of(work, struct sugov_policy, work);
> +
> +	mutex_lock(&sg_policy->work_lock);
> +	__cpufreq_driver_target(sg_policy->policy, sg_policy->next_freq,
> +				CPUFREQ_RELATION_L);

As per here, which I assume matches semantics on that point.

> +	mutex_unlock(&sg_policy->work_lock);
> +
> +	sg_policy->work_in_progress = false;
> +}