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Re: Hyper-threading (was Re: ext3 or xfs for desktop laptop)



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Andy Smith wrote:
> On Sat, Jun 10, 2006 at 10:14:41PM -0500, Ron Johnson wrote:
>> Nate Bargmann wrote:
[snip]
> This is a bit simplistic.  Hyper-Threading (or more correctly, 
> simultaneous multithreading (SMT)) is almost always a win because
>  at any given time a CPU is often waiting for other stages of the
>  pipeline to complete before it can progress with what it is
> being tasked to do.  By having multiple threads of execution it
> can be getting on with something useful more of the time.
> 
> Of course, unless the software being run is paralellizable then 
> very little gains will be realised, but the execution part should
>  never actually get slower.  There have been bugs in the Pentium
> 4 architecture that have caused various software to run slower 
> under hyperthreading, and lack of paralellism can lead to no 
> discernible benefit, but the concept of SMT when done right has 
> no downside from the point of view of a CPU executing 
> instructions.

Thanks for correcting me regarding the mechanics of it.

I stand by my assertion, though, that Intel's HT slows down apps
unless they are very threaded.

- --
Ron Johnson, Jr.
Jefferson LA  USA

Is "common sense" really valid?
For example, it is "common sense" to white-power racists that
whites are superior to blacks, and that those with brown skins
are mud people.
However, that "common sense" is obviously wrong.
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