Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1756740Ab1EQWjU (ORCPT ); Tue, 17 May 2011 18:39:20 -0400 Received: from ogre.sisk.pl ([217.79.144.158]:33389 "EHLO ogre.sisk.pl" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751984Ab1EQWjT (ORCPT ); Tue, 17 May 2011 18:39:19 -0400 From: "Rafael J. Wysocki" To: MyungJoo Ham Subject: Re: [PATCH v2 2/3] PM / DEVFREQ: add example governors Date: Wed, 18 May 2011 00:39:56 +0200 User-Agent: KMail/1.13.6 (Linux/2.6.39-rc7+; KDE/4.6.0; x86_64; ; ) Cc: linux-pm@lists.linux-foundation.org, linux-kernel@vger.kernel.org, "Greg Kroah-Hartman" , Mark Brown , Jiejing Zhang , Pavel Machek , Colin Cross , Nishanth Menon , Thomas Gleixner , Len Brown , Kyungmin Park , myungjoo.ham@gmail.com References: <1305100723-29161-1-git-send-email-myungjoo.ham@samsung.com> <1305100723-29161-2-git-send-email-myungjoo.ham@samsung.com> In-Reply-To: <1305100723-29161-2-git-send-email-myungjoo.ham@samsung.com> MIME-Version: 1.0 Content-Type: Text/Plain; charset="iso-8859-2" Content-Transfer-Encoding: 7bit Message-Id: <201105180039.56806.rjw@sisk.pl> Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 4411 Lines: 132 On Wednesday, May 11, 2011, MyungJoo Ham wrote: > Three CPUFREQ-like governors are provided as examples. > > powersave: use the lowest frequency possible. The user (device) should > set the polling_ms as 0 because polling is useless for this governor. > > performance: use the highest freqeuncy possible. The user (device) > should set the polling_ms as 0 because polling is useless for this > governor. > > simple_ondemand: simplified version of CPUFREQ's ONDEMAND governor. > > When a user updates OPP entries (enable/disable/add), OPP framework > automatically notifies DEVFREQ to update operating frequency > accordingly. Thus, DEVFREQ users (device drivers) do not need to update > DEVFREQ manually with OPP entry updates or set polling_ms for powersave > , performance, or any other "static" governors. Well, do you expect anyone to actually use them? If not, it would make more sense to put them into a doc. Thanks, Rafael > Signed-off-by: MyungJoo Ham > Signed-off-by: Kyungmin Park > --- > drivers/base/power/devfreq.c | 69 ++++++++++++++++++++++++++++++++++++++++++ > include/linux/devfreq.h | 5 +++ > 2 files changed, 74 insertions(+), 0 deletions(-) > > diff --git a/drivers/base/power/devfreq.c b/drivers/base/power/devfreq.c > index 8e2e45b..251d761 100644 > --- a/drivers/base/power/devfreq.c > +++ b/drivers/base/power/devfreq.c > @@ -351,3 +351,72 @@ static int __init devfreq_init(void) > return 0; > } > late_initcall(devfreq_init); > + > +static int devfreq_powersave_func(struct devfreq *df, > + unsigned long *freq) > +{ > + *freq = 0; /* devfreq_do will run "ceiling" to 0 */ > + return 0; > +} > + > +struct devfreq_governor devfreq_powersave = { > + .get_target_freq = devfreq_powersave_func, > +}; > + > +static int devfreq_performance_func(struct devfreq *df, > + unsigned long *freq) > +{ > + *freq = UINT_MAX; /* devfreq_do will run "floor" */ > + return 0; > +} > + > +struct devfreq_governor devfreq_performance = { > + .get_target_freq = devfreq_performance_func, > +}; > + > +/* Constants for DevFreq-Simple-Ondemand (DFSO) */ > +#define DFSO_UPTHRESHOLD (90) > +#define DFSO_DOWNDIFFERENCTIAL (5) > +static int devfreq_simple_ondemand_func(struct devfreq *df, > + unsigned long *freq) > +{ > + struct devfreq_dev_status stat; > + int err = df->profile->get_dev_status(df->dev, &stat); > + unsigned long long a, b; > + > + if (err) > + return err; > + > + /* Set MAX if it's busy enough */ > + if (stat.busy_time * 100 > > + stat.total_time * DFSO_UPTHRESHOLD) { > + *freq = UINT_MAX; > + return 0; > + } > + > + /* Set MAX if we do not know the initial frequency */ > + if (stat.current_frequency == 0) { > + *freq = UINT_MAX; > + return 0; > + } > + > + /* Keep the current frequency */ > + if (stat.busy_time * 100 > > + stat.total_time * (DFSO_UPTHRESHOLD - DFSO_DOWNDIFFERENCTIAL)) { > + *freq = stat.current_frequency; > + return 0; > + } > + > + /* Set the desired frequency based on the load */ > + a = (unsigned long long) stat.busy_time * stat.current_frequency; > + b = div_u64(a, stat.total_time); > + b *= 100; > + b = div_u64(b, (DFSO_UPTHRESHOLD - DFSO_DOWNDIFFERENCTIAL / 2)); > + *freq = (unsigned long) b; > + > + return 0; > +} > + > +struct devfreq_governor devfreq_simple_ondemand = { > + .get_target_freq = devfreq_simple_ondemand_func, > +}; > diff --git a/include/linux/devfreq.h b/include/linux/devfreq.h > index d08e9f5..ec41ba6 100644 > --- a/include/linux/devfreq.h > +++ b/include/linux/devfreq.h > @@ -81,6 +81,11 @@ extern int devfreq_add_device(struct device *dev, > extern int devfreq_remove_device(struct device *dev); > extern int devfreq_update(struct device *dev, bool may_not_exist); > extern int devfreq_tickle_device(struct device *dev, unsigned long duration_ms); > + > +extern struct devfreq_governor devfreq_powersave; > +extern struct devfreq_governor devfreq_performance; > +extern struct devfreq_governor devfreq_simple_ondemand; > + > #else /* !CONFIG_PM_DEVFREQ */ > static int devfreq_add_device(struct device *dev, > struct devfreq_dev_profile *profile, > -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/