[Xenomai] Thermal issue on iMX6q

[Xenomai] Thermal issue on iMX6q

[Thierry Bultel]

Hi,

I am using xenomai-2.6.2.1 on an IMX6q, my problem is clearly not
related to software,
but I am interested in getting the other users feedback about it.

I have measured CPU temperatures greater than 80 degres.
I understand that the thermal management is disabled with xenomai,
because CPU_FREQ is forbidden.

Do other users have experienced such temperatures as well ?
Did they come to the conclusion that a heat dissipator was mandatory ?

Regards
Thierry

Re: [Xenomai] Thermal issue on iMX6q

[Gilles Chanteperdrix]

On 06/28/2013 11:24 AM, Thierry Bultel wrote:

> I understand that the thermal management is disabled with xenomai,
> because CPU_FREQ is forbidden.


If you are using the Freescale kernel, CPU_FREQ should actually be 
enabled. But it is true that the frequency should not be changed after 
Xenomai is started, as Xenomai does not support it. However, if I 
remember correctly, there was a kernel parameter allowing to select a 
frequency at boot time.

-- 
                                                                 Gilles.

Re: [Xenomai] Thermal issue on iMX6q

[Thierry Bultel]

Hi,

I have noticed something really weird.
I was using for months the 3.0.43 kernel from ipipe-gch.git

When the target is idle, I mean, with 4 CPUs at almost 0 % load,
the temperature (/sys/class/thermal/thermal_zone0/temp) is about 66 degrees.
(there is no heat spreader).

With each CPU at 100%, the temperature gets over 90 quickly and the 
target reboots.

Since today, I was -at last- able to apply the latest available ipipe patch
(adeos-ipipe-3.0.43) from xenomai-2.6.git head) on the 3.0.35_4.0.0
kernel from Freescale.

With that kernel, in idle, the temperature is only 44 degrees,
with 4 CPUs to 100% the temperature stabilizes at 60 degrees.

I am a little bit puzzled ... I am obviously using the same config in 
both cases.
Does anyone have an idea ?

Cheers
Thierry

Le 30/06/2013 20:39, Gilles Chanteperdrix a écrit :
> On 06/28/2013 11:24 AM, Thierry Bultel wrote:
>
>> I understand that the thermal management is disabled with xenomai,
>> because CPU_FREQ is forbidden.
>
>
> If you are using the Freescale kernel, CPU_FREQ should actually be 
> enabled. But it is true that the frequency should not be changed after 
> Xenomai is started, as Xenomai does not support it. However, if I 
> remember correctly, there was a kernel parameter allowing to select a 
> frequency at boot time.
>

Re: [Xenomai] Thermal issue on iMX6q

[Gilles Chanteperdrix]

On 09/05/2013 11:32 PM, Thierry Bultel wrote:
> Hi,
> 
> I have noticed something really weird.
> I was using for months the 3.0.43 kernel from ipipe-gch.git
> 
> When the target is idle, I mean, with 4 CPUs at almost 0 % load,
> the temperature (/sys/class/thermal/thermal_zone0/temp) is about 66 degrees.
> (there is no heat spreader).
> 
> With each CPU at 100%, the temperature gets over 90 quickly and the 
> target reboots.
> 
> Since today, I was -at last- able to apply the latest available ipipe patch
> (adeos-ipipe-3.0.43) from xenomai-2.6.git head) on the 3.0.35_4.0.0
> kernel from Freescale.
> 
> With that kernel, in idle, the temperature is only 44 degrees,
> with 4 CPUs to 100% the temperature stabilizes at 60 degrees.
> 
> I am a little bit puzzled ... I am obviously using the same config in 
> both cases.
> Does anyone have an idea ?

Are you sure the CPU is running at the same frequency in both cases?
Have you checked the kernel parameter I talked you about 3 monthes ago?

-- 
                                                                Gilles.

Re: [Xenomai] Thermal issue on iMX6q

[Gilles Chanteperdrix]

On 09/05/2013 11:32 PM, Thierry Bultel wrote:
> Hi,
> 
> I have noticed something really weird.
> I was using for months the 3.0.43 kernel from ipipe-gch.git
> 
> When the target is idle, I mean, with 4 CPUs at almost 0 % load,
> the temperature (/sys/class/thermal/thermal_zone0/temp) is about 66 degrees.
> (there is no heat spreader).
> 
> With each CPU at 100%, the temperature gets over 90 quickly and the 
> target reboots.
> 
> Since today, I was -at last- able to apply the latest available ipipe patch
> (adeos-ipipe-3.0.43) from xenomai-2.6.git head) on the 3.0.35_4.0.0
> kernel from Freescale.
> 
> With that kernel, in idle, the temperature is only 44 degrees,
> with 4 CPUs to 100% the temperature stabilizes at 60 degrees.
> 
> I am a little bit puzzled ... I am obviously using the same config in 
> both cases.
> Does anyone have an idea ?

Also, check the idle routine, maybe the mx6 specific patch removes some
parts of the idle routine because it causes high latencies, which the
mainline I-pipe patch can not do because it does not patch the mx6
specific code.


-- 
                                                                Gilles.