Re: [PATCH 0 of 9] x86/smp function calls: convert x86 tlb flushesto use function calls [POST 2]

[Jeremy Fitzhardinge]

Andi Kleen wrote:
>> nice stuff!
>>     
>
> If only those 35% wouldn't be there ...
>   

Don't pay attention to that number.  It's only the extra latency of a HT
context->HT context function call + tlb flush.  Which means 1) the tlb
is shared anyway, so the extra flush is redundant, 2) they're not really
concurrent, 3) it's going down the single-cpu call, rather than the
multi-cpu one, 4) it's only measuring the latency for a particular tlb
flush, and doesn't take into account any throughput improvements the
extra queueing may add.

I don't really know what the nett consequence of all that is, but it
means the number has almost no bearing on multicore results, esp with >2
cores.

    J
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