Re: Hyper-threading (was Re: ext3 or xfs for desktop laptop)
On Sun, 11 Jun 2006 07:00:55 -0500
Ron Johnson <ron.l.johnson@cox.net> wrote:
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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.
>
It is usually the other way around, it usually slows down apps IF 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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