Messages in this thread | | | From | Nick Piggin <> | Subject | Re: x86: Is there still value in having a special tlb flush IPI vector? | Date | Fri, 1 Aug 2008 11:32:32 +1000 |
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On Friday 01 August 2008 02:48, Ingo Molnar wrote: > * Peter Zijlstra <peterz@infradead.org> wrote:
> > The overhead of that is a smp_mb() and a list_empty() check in > > generic_smp_call_function_single_interrupt() if there is indeed no > > work to do. > > that would be a miniscule cost - cacheline is read-shared amongst cpus > so there's no real bouncing there. So i'm all for it ...
smp_mb would cost some cycles. So would the branch mispredict because list_empty would otherwise normally be taken I think. q likely is not in cache either.
I'm not in favour.
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