On Fri, 13 Jan 2012, V G wrote:

> The way I see it (correct me if I'm wrong), is that the Core i5 has 4
> physical cores, Core i7 has 4 physical cores but reports 8, FX-8150
> has 8 integer cores (and 4 floating point cores).
>
> Anyway, the Core i7 seems to greatly outperform the Core i5 in many
> benchmarks. What are the reasons for this? Is it because of the way
> that it reports another 4 cores to improve SMP? Would performance be
> similar if the feature were enabled in the Core i5?

My understanding is that the i7 can perform hyperthreading (HT) per core=20
so it gives you 4 physical cores + 4 virtual cores.

I belive HT makes use of "dead time" during physical core intruction=20
execution to execute virtual core instructions. i.e. say there is a stall=20
in the physical core instruction execution pipeline (maybe the core needs=20
to get the results of a previous instruction but they aren't ready yet),=20
then the core can use the "stall" to execute instructions that have=20
nothing to do with the thread that is causing the stall, hence guarenteing
(probably) that there is something that can executed.

I'm pretty sure it's not simply a case of saying "report 8 instead of 4".

Regards
Sergio Masci
--=20
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