Re: ondemand governor and passive cooling broken?

[Thomas Renninger <mail@renninger.de>]

Pallipadi, Venkatesh wrote:
>  
> 
>>-----Original Message-----
>>From: Thomas Renninger [mailto:mail@renninger.de] 
>>Sent: Saturday, August 20, 2005 9:49 PM
>>To: Dominik Brodowski
>>Cc: cpufreq@lists.linux.org.uk; Pallipadi, Venkatesh
>>Subject: Re: ondemand governor and passive cooling broken?
>>
>>Hi,
>>
>>This makes ondemand governor aware of thermal limits.
>>The policy was buffered and new policy values never reached 
>>the governor.
> 
> I don't think there is an issue with buffering here.
> This_dbs_info->cur_policy is a pointer to the cpufreq policy (and not
> allocated by ondemand governor). So, any change to max/min in cpufreq
> should be automatically getting reflected. Atleast that was the intent
> with having policy pointer. If it is not happening then that should be a
> bug. I don't think that this memcpy is required here.
> 
You are right. I tried to reproduce this problem with a powernow-k8 machine
and thermal cooling worked just fine.

>>I just used the cpufreq_get_policy call every time the load is checked,
>>maybe the new policy should be made available via notifier as 
>>it is done
>>for the cur_freq in the userspace governor?
>>If this sounds reasonable I can come up with a bigger patch on Monday.
>>
>>However, thermal cooling still does not always work right:
>>
>> - Sometimes the limit is not decreased correctly in polling 
>>frequency time
>>   (I saw it at max for more than 20 secs, polling freq 5 
>>secs, passive tp exceeded).
>>   Strange enough, that seems to happen only in rare cases.
>> - I also saw the limit stuck at lowest frequency even after 
>>getting back in
>>   normal temperature zones.
> 
> I think we need to do some more things to intergrate cpufreq and thermal
> cooling. Especially in relation to polling frequency. Probably, ondemand
> governor should slow down its polling interval to something higher than
> thermal polling frequency as soon as it notices the passive cooling is
> on.

Don't know. I will try to get a speedstep-centrino machine and have a look
whether this makes a difference and also play around a bit with thermal polling freq
and ondemand configs. Do you think this could be a driver specific problem?

Thanks,

      Thomas