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

[Peter Zijlstra]

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.