[Cbe-oss-dev] PS3 performance analysis - errors on loading cellperfctr module

[Geoff Levand]

Dimitar Lukarski wrote:
> Geoff Levand wrote:
>> Dimitar Lukarski wrote:
>>   
>>> Hello,
>>>
>>>     I am try to get some performance analysis on PS3 running under
>>> Yellow Dog Linux 5.0 and IBM SDK 2.1.
>>>     I recompile the newest kernel 2.6.23 with oprofile modules. I also
>>> installed cellperfctr-tools-2007.03.19-1.ppc64.rpm plus the modules. But
>>> when I try to load it - it gives errors.
>>>
>>>     Is it problem with my kernel compilation or just PS3 does not
>>> support SPU sampling ?
>>>
>>>  
>>> # modprobe cellperfctr
>>> FATAL: Error inserting cellperfctr
>>> (/lib/modules/2.6.23custom/extra/cellperfctr.ko): Unknown symbol in
>>> module, or unknown parameter (see dmesg)
>>>
>>>
>>> # dmesg | tail
>>> cellperfctr: Unknown symbol cbe_read_pm07_control
>>> cellperfctr: Unknown symbol cbe_read_pm
>>> cellperfctr: Unknown symbol cbe_write_pm07_control
>>> cellperfctr: Unknown symbol cbe_read_ctr
>>> cellperfctr: Unknown symbol cbe_read_trace_buffer
>>> cellperfctr: Unknown symbol rtas_call
>>> cellperfctr: Unknown symbol cbe_write_phys_ctr
>>> cellperfctr: Unknown symbol cbe_write_ctr
>>> cellperfctr: Unknown symbol cbe_write_pm
>>> cellperfctr: Unknown symbol rtas_token
>>>     
>>
>>
>> The Cell's hardware profiling support is a hypervisor resource, so on PS3
>> you cannot access those resources directly as you can when Linux is running
>> on the raw hardware.  The IBM Cell Blade for example runs without a hypervisor,
>> and it uses cellperfctr.ko.  There currently is no Linux profiling support
>> on PS3 other than the standard oprofile timer based sampling that the
>> generic powerpc code provides.
>>
>> In general there is a desire to provide some kind of Cell specific profiling
>> support for the PS3, but nothing has been announced. 
>>
>> -Geoff 
>>
>>
>>   
> 
>  So, I can make profiling only on the PPU but not on the SPU, because
> of the hypervisor resource on PS3. Pity :(

Well yes and no.  

The fact that profiling registers are a hypervisor resource is in no way
specific to the PS3, that is a design of the Cell processor.  In general
it is a good design to have such resources controlled by a hypervisor,
otherwise code running in an LPAR could gain control of the system's
processors.

-Geoff