Re: [Bug 4379] Default sampling rates for ondemand governor are too high on a amd64

From: Eric Piel <Eric.Piel@tremplin-utc.net>
To: bugme-daemon@bugzilla.kernel.org
Cc: linux@brodo.de, cpufreq@www.linux.org.uk
Subject: Re: [Bug 4379] Default sampling rates for ondemand governor are too high on a amd64
Date: Wed, 16 Nov 2005 08:50:42 +0100	[thread overview]
Message-ID: <437AE4D2.2030503@tremplin-utc.net> (raw)
In-Reply-To: <200511152159.jAFLxHL4003020@fire-2.osdl.org>

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15.11.2005 22:59, bugme-daemon@bugzilla.kernel.org wrote/a écrit:
> http://bugzilla.kernel.org/show_bug.cgi?id=4379
> 
> 
> 
> 
> 
> ------- Additional Comments From linux@brodo.de  2005-11-15 13:53 -------
> Is this problem still present in 2.6.14?
> 
I think so.

Well, I've got a patch that should fix it. It make the polling frequency 
10 times faster than it used to be. This is valid _only_ for kernel >= 
2.6.15-rc1 because there is now a check to avoid polling too fast. I've 
tested it here, on my pentium III it works.

Venki, do you see any problem with this patch?

Eric

-- 
From: Eric Piel <eric.piel@tremplin-utc.net>

Make the polling frequency 10 times faster than it used to be, now that 
there is a check to avoid too high freqencies. Solve problems with 
hardwares which have a long transition latency.

Signed-off-by: Eric Piel <eric.piel@tremplin-utc.net>
-- 

[-- Attachment #2: cpufreq-ondemand-more-frequent-polling-2.6.15-rc1.patch --]
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--- linux-2.6.14/drivers/cpufreq/cpufreq_ondemand.c.bak	2005-11-16 08:35:14.000000000 +0100
+++ linux-2.6.14/drivers/cpufreq/cpufreq_ondemand.c	2005-11-16 08:36:57.000000000 +0100
@@ -39,7 +39,7 @@
 
 /* 
  * The polling frequency of this governor depends on the capability of 
- * the processor. Default polling frequency is 1000 times the transition
+ * the processor. Default polling frequency is 100 times the transition
  * latency of the processor. The governor will work on any processor with 
  * transition latency <= 10mS, using appropriate sampling 
  * rate.
@@ -53,7 +53,7 @@ static unsigned int 				def_sampling_rat
 #define MIN_STAT_SAMPLING_RATE			(MIN_SAMPLING_RATE_RATIO * jiffies_to_usecs(10))
 #define MIN_SAMPLING_RATE			(def_sampling_rate / MIN_SAMPLING_RATE_RATIO)
 #define MAX_SAMPLING_RATE			(500 * def_sampling_rate)
-#define DEF_SAMPLING_RATE_LATENCY_MULTIPLIER	(1000)
+#define DEF_SAMPLING_RATE_LATENCY_MULTIPLIER	(100)
 #define DEF_SAMPLING_DOWN_FACTOR		(1)
 #define MAX_SAMPLING_DOWN_FACTOR		(10)
 #define TRANSITION_LATENCY_LIMIT		(10 * 1000)

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