linux-kernel - Re: thermal governor: does it actually work??

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Date:	Fri, 22 Feb 2013 06:33:04 +0100
From:	Peter Feuerer <peter@...e.net>
To:	Zhang Rui <rui.zhang@...el.com>, Borislav Petkov <bp@...en8.de>
Cc:	Andreas Mohr <andi@...as.de>, linux-kernel@...r.kernel.org,
	Durgadoss R <durgadoss.r@...el.com>
Subject: Re: thermal governor: does it actually work??

Adding Boris,

sorry, I can't do anything currently, I'm down with influenza.

kind regards,
--peter;

Zhang Rui writes:

> On Thu, 2013-02-14 at 16:32 +0100, Andreas Mohr wrote:
>> For me after having loaded acerhdf the fan never stops (with kernelmode
>> active), despite staying safely below trip point
>> (acerhdf_set_cur_state() actually never gets called).
> 
> BTW, could you please check if this one fixes the problem for you?
> http://git.kernel.org/?p=linux/kernel/git/rzhang/linux.git;a=commit;h=b8bb6cb999858043489c1ddef08eed2127559169
> 
> thanks,
> rui
>> And AFAIR in a 3.2.0 kernel acerhdf fan operation seemed to just work
>> (i.e., no fan for low temps, from the beginning).
>> Needless to say 3.2.0 didn't even feature all the modern thermal
>> governor crapyard yet ;)
>> (ok, well, it's more complex but it's also a very nice environment capability)
>> 
>> 3.8-rc7:
>> CONFIG_ACPI_THERMAL=m
>> CONFIG_THERMAL=m
>> CONFIG_THERMAL_HWMON=y
>> CONFIG_THERMAL_DEFAULT_GOV_STEP_WISE=y
>> # CONFIG_THERMAL_DEFAULT_GOV_FAIR_SHARE is not set
>> # CONFIG_THERMAL_DEFAULT_GOV_USER_SPACE is not set
>> CONFIG_FAIR_SHARE=y
>> CONFIG_STEP_WISE=y
>> # CONFIG_USER_SPACE is not set
>> # CONFIG_CPU_THERMAL is not set
>> 
>> 
>> 
>> Terminology in this area seems to be quite a bit off, too, at several
>> docs places, at least according to my understanding:
>> 
>> e.g. drivers/thermal/step_wise.c has the following comment:
>> 
>> /**
>>  * step_wise_throttle - throttles devices associated with the given zone
>>  * @tz - thermal_zone_device
>>  * @trip - the trip point
>>  * @trip_type - type of the trip point
>>  *
>>  * Throttling Logic: This uses the trend of the thermal zone to
>>  * throttle.
>>  * If the thermal zone is 'heating up' this throttles all the cooling
>>  * devices associated with the zone and its particular trip point, by
>>  * one
>>  * step. If the zone is 'cooling down' it brings back the performance of
>>  * the devices by one step.
>> 
>> 
>> 
>> if ... heating up ... throttles ...
>> Sorry, but at least for P4 clockmod stuff (or some such), throttle
>> states (P1...P8 IIRC) meant that the CPU operation was *reduced*,
>> i.e. with pause intervals.
>> And the translation of throttle clearly says that it does go that way
>> and not the other way...
>> (yes, you managed to confuse me that much that I even had to look up
>> things to verify)
>> 
>> ... cooling down ... brings back ...
>> This should certainly be worded "reduces" or some such.
>> 
>> So, any idea why I'm missing callbacks in acerhdf (if that is what I'm
>> supposed to expect to happen)?
>> Kernel bug, .config mistake, missing/wrong user-side setup?
>> 
>> Needless to say if kernel bug this ought to be fixed pre-3.8 ideally.
>> 
>> Thanks,
>> 
>> Andreas Mohr
> 
> 
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