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Re: [SLUG] Re: pentium M series


On Sun, 2005-12-25 at 09:34 +1100, O Plameras wrote:
> James Gregory wrote:
> 
> >
> >That's exactly right. And if you compile without CONFIG_SMP, that's what
> >gets built into your kernel. You can get away with it because of the
> >clever way in which a CPU does one thing at a time; there is no "true"
> >parallelism.
> >
> 
> By the way, is it not true that 'pipelining'  that's a feature of x86 
> CPU's starting
> with i586 which I have pointed out in one of my previous post  is 
> (another name)
> implementation of 'parallel' processing ?  This means that more than one 
> instructions may be
> executed in one clock cycle.  This is implemented by using a bus 
> interface unit
> (BIU) and an execution unit. Experts on Intel Arch may confirm the 
> truthfullness or
> falsehood of this assertion. (I'm not an expert, I just know by 
> researching).
> 
> With pipelining,  the CPU overlaps instruction fetching and decoding with
> instruction execution, i.e., while one instruction is executing BIU is 
> fetching
> and decoding the next instruction. So, assuming you're willing to add 
> hardware
> you can execute more and more operations in parallel.
> 
> So, in this way there is true parallelism in x86 arch.
> 
> Just a clarification.

Holy shit! You are soooo off base here its not funny. 'More than one
thing per clock cycle' -> What do clock cycles have to do with
parallelism? Nothing. Concurrency means 'concurrent'. If two operations
complete in one clock cycle *in series*, then its not parallel. Its
fast, but not parallel.

If you want an cpu architecture that performs *concurrent operations* in
one cpu, look into EPIC or IA-64.

Just a un-clarification.

Rob


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