linux-kernel - Re: [RFT][PATCH 1/3] PM: QoS: Introduce frequency QoS

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Message-ID: <VI1PR04MB70234EB305F60855491EBFDDEE6A0@VI1PR04MB7023.eurprd04.prod.outlook.com>
Date:   Thu, 24 Oct 2019 19:34:59 +0000
From:   Leonard Crestez <leonard.crestez@....com>
To:     "Rafael J. Wysocki" <rjw@...ysocki.net>,
        Viresh Kumar <viresh.kumar@...aro.org>
CC:     Linux PM <linux-pm@...r.kernel.org>,
        Linux ACPI <linux-acpi@...r.kernel.org>,
        LKML <linux-kernel@...r.kernel.org>,
        Sudeep Holla <sudeep.holla@....com>,
        Dmitry Osipenko <digetx@...il.com>
Subject: Re: [RFT][PATCH 1/3] PM: QoS: Introduce frequency QoS

On 24.10.2019 22:01, Leonard Crestez wrote:
> On 16.10.2019 13:48, Rafael J. Wysocki wrote:
>> From: Rafael J. Wysocki <rafael.j.wysocki@...el.com>
>>
>> Introduce frequency QoS, based on the "raw" low-level PM QoS, to
>> represent min and max frequency requests and aggregate constraints.
>>
>> The min and max frequency requests are to be represented by
>> struct freq_qos_request objects and the aggregate constraints are to
>> be represented by struct freq_constraints objects.  The latter are
>> expected to be initialized with the help of freq_constraints_init().
>>
>> The freq_qos_read_value() helper is defined to retrieve the aggregate
>> constraints values from a given struct freq_constraints object and
>> there are the freq_qos_add_request(), freq_qos_update_request() and
>> freq_qos_remove_request() helpers to manipulate the min and max
>> frequency requests.  It is assumed that the the helpers will not
>> run concurrently with each other for the same struct freq_qos_request
>> object, so if that may be the case, their uses must ensure proper
>> synchronization between them (e.g. through locking).
>>
>> In addition, freq_qos_add_notifier() and freq_qos_remove_notifier()
>> are provided to add and remove notifiers that will trigger on aggregate
>> constraint changes to and from a given struct freq_constraints object,
>> respectively.
>>
>> Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@...el.com>
>> ---
>>    include/linux/pm_qos.h |   44 ++++++++
>>    kernel/power/qos.c     |  240 +++++++++++++++++++++++++++++++++++++++++++++++++
>>    2 files changed, 284 insertions(+)
>>
>> Index: linux-pm/include/linux/pm_qos.h
>> ===================================================================
>> --- linux-pm.orig/include/linux/pm_qos.h
>> +++ linux-pm/include/linux/pm_qos.h
>> @@ -267,4 +267,48 @@ static inline s32 dev_pm_qos_raw_resume_
>>    }
>>    #endif
>>    
>> +#define FREQ_QOS_MIN_DEFAULT_VALUE	0
>> +#define FREQ_QOS_MAX_DEFAULT_VALUE	(-1)
>> +
>> +enum freq_qos_req_type {
>> +	FREQ_QOS_MIN = 1,
>> +	FREQ_QOS_MAX,
>> +};
>> +
>> +struct freq_constraints {
>> +	struct pm_qos_constraints min_freq;
>> +	struct blocking_notifier_head min_freq_notifiers;
>> +	struct pm_qos_constraints max_freq;
>> +	struct blocking_notifier_head max_freq_notifiers;
> 
> These min/max_freq_notifiers fields seem unused? They're initialized but
> the freq_qos_add/remove_notifier calls use min/max_freq.notifiers directly.
> 
> Should probably just be dropped.

Never mind, I see now that pm_qos_constraints.notifiers is actually a 
pointer to notifier block provided by somebody else.

--
Regards,
Leonard