On 10/16/2013 10:00 AM, Anshuman Khandual wrote:
> On 10/14/2013 11:49 AM, Michael Ellerman wrote:
>> On Fri, Oct 11, 2013 at 10:02:28AM +0530, Anshuman Khandual wrote:
>>> On 10/11/2013 07:41 AM, Michael Ellerman wrote:
>>>> On Thu, Oct 10, 2013 at 02:20:22PM +0530, Anshuman Khandual wrote:
>>>>
>>>>> Even I think this is not right. Instruction sampling should have been
>>>>> enabled before we enable PMU interrupts. Else there is a small window
>>>>> of time where we could have the PMU enabled with events (which requires
>>>>> sampling) without the sampling itself being enabled in MMCRA.
>>>>
>>>> Yes I agree. That's a separate bug, which we'll need to test on all the
>>>> book3s
>>>> platforms we have perf support for.
>>>
>>> Okay, I guess any platform which supports sampling will definitely want to
>>> have
>>> it enabled before we can set the events to count on PMU. Can you think of
>>> any
>>> problem which can arise if we move it before the enabling the PMU back ?
>>> Else
>>> we can fix this easily.
>>
>> In theory it should be a trivial change. But hardware can behave in
>> strange ways, it's possible on some old chip we need to do it the
>> current way for some reason.
>>
>> So although I don't think it will be a problem, it could be, so we
>> will need to test it thoroughly.
>
> So which are the HW chips, you would like to test this fix for possible
> problems ?
>
Michael,
Any updates on this patch ?
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