linux-kernel - Re: [PATCH] cpufreq: fix conservative/ondemand behaviour with ignore_nice

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Message-ID: <20091110222038.GA32028@linux-os.sc.intel.com>
Date:	Tue, 10 Nov 2009 14:20:38 -0800
From:	"Pallipadi, Venkatesh" <venkatesh.pallipadi@...el.com>
To:	Alexander Miller <Miller@....uni-stuttgart.de>
Cc:	"linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
	"cpufreq@...r.kernel.org" <cpufreq@...r.kernel.org>,
	Dave Jones <davej@...hat.com>
Subject: Re: [PATCH] cpufreq: fix conservative/ondemand behaviour with ignore_nice_load

On Tue, Nov 10, 2009 at 11:42:02AM -0800, Pallipadi, Venkatesh wrote:
> >-----Original Message-----
> >From: cpufreq-owner@...r.kernel.org 
> >[mailto:cpufreq-owner@...r.kernel.org] On Behalf Of Alexander Miller
> >Sent: Friday, November 06, 2009 8:27 AM
> >To: linux-kernel@...r.kernel.org
> >Cc: cpufreq@...r.kernel.org; Dave Jones
> >Subject: [PATCH] cpufreq: fix conservative/ondemand behaviour 
> >with ignore_nice_load
> >
> >Remove conversion of nice load to microseconds which caused addition
> >of times measured in different units and thus unreasonable behaviour
> >with both governors.                                                  
> 
> Can you describe the "unresonable behavior" you are seeing. Is it
> with NO_HZ enabled or disabled?
> 
> I see there can be a problem with this code when NO_HZ is disabled.
> But, the patch below is not the right solution as it will result in
> Adding times in different units with NO_HZ enabled.
> 
> Thanks,
> Venki

Does the below test patch (only compile tested) resolve the problem you
are seeing?

Thanks,
Venki

---
 drivers/cpufreq/cpufreq_conservative.c |    4 ++--
 drivers/cpufreq/cpufreq_ondemand.c     |    4 ++--
 2 files changed, 4 insertions(+), 4 deletions(-)

diff --git a/drivers/cpufreq/cpufreq_conservative.c b/drivers/cpufreq/cpufreq_conservative.c
index bc33ddc..c7b081b 100644
--- a/drivers/cpufreq/cpufreq_conservative.c
+++ b/drivers/cpufreq/cpufreq_conservative.c
@@ -116,9 +116,9 @@ static inline cputime64_t get_cpu_idle_time_jiffy(unsigned int cpu,
 
 	idle_time = cputime64_sub(cur_wall_time, busy_time);
 	if (wall)
-		*wall = cur_wall_time;
+		*wall = (cputime64_t)jiffies_to_usecs(cur_wall_time);
 
-	return idle_time;
+	return (cputime64_t)jiffies_to_usecs(idle_time);;
 }
 
 static inline cputime64_t get_cpu_idle_time(unsigned int cpu, cputime64_t *wall)
diff --git a/drivers/cpufreq/cpufreq_ondemand.c b/drivers/cpufreq/cpufreq_ondemand.c
index 071699d..4b34ade 100644
--- a/drivers/cpufreq/cpufreq_ondemand.c
+++ b/drivers/cpufreq/cpufreq_ondemand.c
@@ -133,9 +133,9 @@ static inline cputime64_t get_cpu_idle_time_jiffy(unsigned int cpu,
 
 	idle_time = cputime64_sub(cur_wall_time, busy_time);
 	if (wall)
-		*wall = cur_wall_time;
+		*wall = (cputime64_t)jiffies_to_usecs(cur_wall_time);
 
-	return idle_time;
+	return (cputime64_t)jiffies_to_usecs(idle_time);
 }
 
 static inline cputime64_t get_cpu_idle_time(unsigned int cpu, cputime64_t *wall)
-- 
1.6.0.6

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