Re: CVS commit: src/sys/arch/x86/x86

[Christoph Egger <Christoph_Egger%gmx.de@localhost>]

On 05/16/12 14:00, Jean-Yves Migeon wrote:

> Le 16/05/12 10:45, Christoph Egger a écrit :
>> On 05/13/12 13:24, Martin Husemann wrote:
>>
>>> On Sun, May 13, 2012 at 01:04:15PM +0200, Jean-Yves Migeon wrote:
>>>> Are you sure that moving to low priority xcalls is the way to go? You
>>>> can end up with CPUs not being updated because they are offline.
>>>
>>> Curiously, while I could reproduce the crash before this commit, I am
>>> unable to reproduce it in any testing without the actual ucode update
>>> happening - and I can not spot a bug in the xcall code that tries to
>>> make
>>> sure the number of cpus that did run the callback is == the expected
>>> count
>>> before returning.
>>>
>>> This clearly needs full analyzis.
>>
>> I am pleased to revert this change once this xcall(9) issue has been
>> fixed.
> 
> Sure, however I can't see where the xcall(9) code goes wrong. Care to
> give more details, please? I cannot reproduce it on my side.

It is reproducable when the callback function makes an output with
printf() or aprint_*().

> I am using xcall(9) to flush CPU-bound pool caches and having this sort
> of bug can definitely cause serious cache incoherency that are hard to
> track down afterwards.
> 
> Is it specific to high priority xcalls?


No.

Christoph