Hard hang with powerd

[Nate Lawson]

Maxim Maximov wrote:
> Bruno Ducrot wrote:
> 
>> On Tue, Sep 20, 2005 at 06:04:40PM +0400, Maxim Maximov wrote:
>>
>>> Bruno Ducrot wrote:
>>>
>>>> On Tue, Sep 20, 2005 at 04:35:24PM +0400, Maxim Maximov wrote:
>>>>
>>>>
>>>>> Hi, all.
>>>>>
>>>>>     I've got hard hangs with latest CURRENT in a few seconds after 
>>>>>     enabling powerd. Here's loader.conf:
>>>>>
>>>>> # cat /boot/loader.conf
>>>>> hw.psm.synaptics_support=1
>>>>> debug.mpsafevfs=1
>>>>> acpi_perf_load="YES"
>>>>> cpufreq_load="YES"
>>>>> debug.acpi.disabled="sysres"
>>>>> bcmwl5_sys_load="YES"
>>>>>
>>>>>     What else can I do to help debug it?
>>>>>
>>>>
>>>>
>>>> The 2 logical CPUs need to set the same MSRs at the same time,
>>>> but if the second one is forced to be idle, I'm not sure if p4tcc will
>>>> work fine.
>>>>
>>>> Therefore, I'm wondering if this hard hang happens with a SMP kernel
>>>> and hyperthreading is enabled, or if this happens with a UP kernel.
>>>>
>>>
>>> Yes, kernel is SMP one.
>>>
>>> # sysctl machdep.hyperthreading_allowed
>>> machdep.hyperthreading_allowed: 1
>>>
>>
>> It's weird.  Could you please try with a kernel without SMP for
>> testing purpose?
>>
> 
> It's fine. Now I'm running UP kernel with 'powerd -v'

Bruno, can you expand more on what you think the problem is?  The p4tcc 
driver writes to the MSR on all CPUs, including logical ones.  We switch 
cpus using sched_bind().  So the thread will run on the first CPU, write 
to the MSR, then switch to the second CPU and write to the MSR.  I 
thought this is how the datasheet says the thermal MSR must be used on 
SMP.  It's also what Linux does I believe.

-- 
Nate