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From: Kevin Hilman <khilman@ti.com>
To: myungjoo.ham@gmail.com
Cc: Len Brown <len.brown@intel.com>,
	Greg Kroah-Hartman <gregkh@suse.de>,
	Kyungmin Park <kyungmin.park@samsung.com>,
	Thomas Gleixner <tglx@linutronix.de>,
	linux-pm@lists.linux-foundation.org
Subject: Re: [PATCH v4 0/3] DEVFREQ, DVFS framework for non-CPU devices
Date: Wed, 03 Aug 2011 11:33:35 -0700	[thread overview]
Message-ID: <87aabq5oqo.fsf@ti.com> (raw)
In-Reply-To: <CAJ0PZbTMn_pzFBWbhtMrMo9ZGsnwMNKENgMSDa=oOZCrGh03Gg@mail.gmail.com> (MyungJoo Ham's message of "Wed, 3 Aug 2011 16:03:58 +0900")

MyungJoo Ham <myungjoo.ham@samsung.com> writes:

> On Wed, Aug 3, 2011 at 7:02 AM, Kevin Hilman <khilman@ti.com> wrote:

[...]

>> Maybe I'm not understanding the usage of it fully, but that seems like
>> hard-coding policy into the framework that might not be appropriate.
>> For example, what if there are other devices with constraints such that
>> they cannot currently scale frequency/voltage?
>>
>> Mabye MyungJoo can explain in more detail the usecases for tickle?
>
> Tickle is not for QoS between devices. It is for faster reaction to
> (human) user inputs at DVFS side where waiting for DVFS's reaction
> takes too much time and reducing polling interval costs too much. 

This is exactly what quality of service (QoS) is about.

The user (whether it's a human user input or another device) has low
quality and expects higher quality.  It wants to request better quality,
so it needs a way to request it.   

The proposed "tickle" approach proposed here is simply a "request max
frequency for duration X" QoS request.

Kevin

  parent reply	other threads:[~2011-08-03 18:33 UTC|newest]

Thread overview: 30+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2011-07-15  8:11 [PATCH v4 0/3] DEVFREQ, DVFS framework for non-CPU devices MyungJoo Ham
2011-07-15  8:11 ` [PATCH v4 1/3] PM: Introduce DEVFREQ: generic DVFS framework with device-specific OPPs MyungJoo Ham
2011-08-02 18:45   ` Kevin Hilman
2011-08-03  8:06     ` MyungJoo Ham
2011-08-02 21:56   ` Kevin Hilman
2011-08-03  6:02     ` MyungJoo Ham
2011-07-15  8:11 ` [PATCH v4 2/3] PM / DEVFREQ: add example governors MyungJoo Ham
2011-07-15  8:11 ` [PATCH v4 3/3] PM / DEVFREQ: add sysfs interface (including user tickling) MyungJoo Ham
2011-06-09 17:11   ` Pavel Machek
2011-07-19  2:14     ` MyungJoo Ham
2011-07-28 22:10 ` [PATCH v4 0/3] DEVFREQ, DVFS framework for non-CPU devices Rafael J. Wysocki
2011-07-29  4:46   ` Turquette, Mike
2011-07-29  9:10     ` Rafael J. Wysocki
2011-07-30  1:02       ` Turquette, Mike
2011-07-30 21:23         ` Rafael J. Wysocki
2011-08-01 21:47           ` Turquette, Mike
2011-08-01  6:22         ` MyungJoo Ham
2011-08-01 22:01           ` Turquette, Mike
2011-08-02  7:17             ` MyungJoo Ham
2011-08-02 22:02   ` Kevin Hilman
2011-08-03  7:03     ` MyungJoo Ham
2011-08-03 17:31       ` Turquette, Mike
2011-08-03 18:33       ` Kevin Hilman [this message]
2011-08-04  8:15         ` MyungJoo Ham
2011-08-04 21:59           ` Turquette, Mike
2011-08-05  6:18             ` MyungJoo Ham
2011-08-08 19:13               ` Turquette, Mike
2011-08-09  5:27                 ` MyungJoo Ham
2011-08-11  1:28                   ` Turquette, Mike
2011-08-17 10:07                     ` MyungJoo Ham

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