Re: [PATCH v7 8/8] x86/tlb: just do tlb flush on one of siblings ofSMT

[Borislav Petkov]

On Thu, May 24, 2012 at 01:12:46PM +0800, Alex Shi wrote:
> On 05/24/2012 09:46 AM, Andrew Lutomirski wrote:
> 
> > On Wed, May 23, 2012 at 10:15 AM, Peter Zijlstra <peterz@xxxxxxxxxxxxx> wrote:
> >> On Wed, 2012-05-23 at 19:09 +0200, Peter Zijlstra wrote:
> >>>> There is no comment or anything else indicating that this is
> >>>> suitable for dual-thread CPUs only - when there are more than
> >>>> 2 threads per core, the intended effect won't be achieved.
> >>>
> >>> Why would that be? Won't higher thread count still share the same
> >>> resources just more so?
> >>
> >> Ah, I see, you're saying his code is buggy for >2 threads. Agreed.
> >>
> > 
> > An evil knob to statically choose which SMT sibling gets the interrupt
> > would be nice.  Then my compute-intensive thread could be (mostly)
> > unaffected by the other thread on a different core that calls munmap
> > frequently.
> 
> How to know we are in such situation? :)

Please, not yet another knob, we have too many as it is.

Can't you figure this out from the topology, smt siblings or whatever
this is called:

/sys/devices/system/cpu/cpu0/topology/thread_siblings

?

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Boris.

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