Re: [RFC PATCH 0/2] x86: Fix missing core serialization on migration

[Daniel Bristot de Oliveira]

On 11/14/2017 07:17 PM, Peter Zijlstra wrote:
> On Tue, Nov 14, 2017 at 07:01:55PM +0100, Daniel Bristot de Oliveira wrote:
>> On 11/14/2017 06:40 PM, Peter Zijlstra wrote:
>>> On Tue, Nov 14, 2017 at 06:17:13PM +0100, Daniel Bristot de Oliveira wrote:
>>>
>>>> IIRC, if the dest cpu is idle and the system is with idle=poll, no IPI
>>>> is fired as well, but that is not a very common case.
>>>
>>> You're thinking about wake from idle? That is almost always without IPI,
>>> even without idle=poll.
>>>
>>
>> I meant the resched_curr(rq) of an rq on another CPU. If the dest is
>> idle && idle=poll, the IPI will not be send.
> 
> I'm saying the IPI will not be send even without idle=poll. MWAIT based
> idle will also have TIF_POLLING_NRFLAG set.
> 

Yeah! you are right! I missed that point... sorry :-)

-- Daniel