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

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Date:	Tue, 19 Feb 2013 23:35:23 +0800
From:	Zhang Rui <rui.zhang@...el.com>
To:	Andreas Mohr <andi@...as.de>
Cc:	linux-kernel@...r.kernel.org, Durgadoss R <durgadoss.r@...el.com>,
	peter@...e.net
Subject: Re: thermal governor: does it actually work??

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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