linux-kernel - Re: [PATCH] cpufreq: Fix ondemand governor powersave

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Message-ID: <20110302160033.GA27760@redhat.com>
Date:	Wed, 2 Mar 2011 11:00:34 -0500
From:	Dave Jones <davej@...hat.com>
To:	Youquan Song <youquan.song@...ux.intel.com>
Cc:	Andrew Morton <akpm@...ux-foundation.org>, arjan@...ux.intel.com,
	venki@...gle.com, youquan.song@...el.com,
	cpufreq-list@...r.kernel.org, linux-kernel@...r.kernel.org,
	vincent.guittot@...aro.org
Subject: Re: [PATCH] cpufreq: Fix ondemand governor powersave_bias execution
 time misuse

On Wed, Mar 02, 2011 at 01:58:02PM -0500, Youquan Song wrote:
 >  
 > > Where are we with this patch?  Still needed in curent mainline?
 > Do need it by current mainline. Without the patch, the ondemand
 > power_bias feature is broken and does not work at all.
 > Please take it.

This patch from Vincent Guittot is also pending, which seems to achieve
the same thing ?


commit 1f5a2969af7e0d040876c7ff25308c840eef18d4
Author: Vincent Guittot <vincent.guittot@...aro.org>
Date:   Mon Feb 7 17:14:25 2011 +0100

    [CPUFREQ] calculate delay after dbs_check_cpu
    
    calculate ondemand delay after dbs_check_cpu call because it can
    modify rate_mult value
    
    use freq_lo_jiffies value for the sub sample period of powersave_bias mode
    
    Signed-off-by: Vincent Guittot <vincent.guittot@...aro.org>
    Signed-off-by: Dave Jones <davej@...hat.com>

diff --git a/drivers/cpufreq/cpufreq_ondemand.c b/drivers/cpufreq/cpufreq_ondemand.c
index c631f27..b4e1f98 100644
--- a/drivers/cpufreq/cpufreq_ondemand.c
+++ b/drivers/cpufreq/cpufreq_ondemand.c
@@ -644,12 +644,7 @@ static void do_dbs_timer(struct work_struct *work)
 	unsigned int cpu = dbs_info->cpu;
 	int sample_type = dbs_info->sample_type;
 
-	/* We want all CPUs to do sampling nearly on same jiffy */
-	int delay = usecs_to_jiffies(dbs_tuners_ins.sampling_rate
-		* dbs_info->rate_mult);
-
-	if (num_online_cpus() > 1)
-		delay -= jiffies % delay;
+	int delay;
 
 	mutex_lock(&dbs_info->timer_mutex);
 
@@ -662,10 +657,20 @@ static void do_dbs_timer(struct work_struct *work)
 			/* Setup timer for SUB_SAMPLE */
 			dbs_info->sample_type = DBS_SUB_SAMPLE;
 			delay = dbs_info->freq_hi_jiffies;
+		} else {
+			/* We want all CPUs to do sampling nearly on
+			 * same jiffy
+			 */
+			delay = usecs_to_jiffies(dbs_tuners_ins.sampling_rate
+				* dbs_info->rate_mult);
+
+			if (num_online_cpus() > 1)
+				delay -= jiffies % delay;
 		}
 	} else {
 		__cpufreq_driver_target(dbs_info->cur_policy,
 			dbs_info->freq_lo, CPUFREQ_RELATION_H);
+		delay = dbs_info->freq_lo_jiffies;
 	}
 	queue_delayed_work_on(cpu, kondemand_wq, &dbs_info->work, delay);
 	mutex_unlock(&dbs_info->timer_mutex);
--
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