On 12/5/05, Gilboa Davara <[EMAIL PROTECTED]> wrote:
> On Mon, 2005-12-05 at 17:58 +0200, Oded Arbel wrote:
> > On Monday, 5 בDecember 2005 17:05, Gilboa Davara wrote:
> > > Either way, Intel is dumping Hyper-threading in future CPUs. In the
> > > end, HT was nothing more then a marketing ploy designed to save a bad
> > > core design. (The "I've got too many stalled pipelines" P4)
> >
> > I'm not sure why you say that - I haven't heard of any future intel
> > plans to drop HT, OTOH intel is bringing HT to the Itanium line
> > ("tukwial" or whatever they name it today), Sun has supposedly "4 way"
> > hyperthreading in their Niagara chips, and there are some rumors
> > (nothing I can verify) on AMD bringing out hyperthreaded Opterons in
> > 2007.
>
> You seem to confuse multiple-cores and DSMT * (or some sort) with
> Hyper-threading.
> By design, Hyper-threading is a very interesting idea to increase each
> core's IPC (by utilization stalled pipe-lines [cache-miss] in-favor of
> another "thread") However, due to the problematic design of the P4
> itself (very limited bandwidth, small L1, very limited branch history
> and register files, etc) and the fact that Hyper-threading was added as
> an after-thought to the P4 in-order to improve its lack-luster IPC the
> end-result was less then impressive. (Googling around seems to suggest a
> +10%/-10% performance diff... nothing to write home about)
>
> The idea of having multiple logical cores in-order to improve
> performance is nothing new. Intel's implementation just sucks.
>
> Oh... and all future Intel CPUs will be built around the Pentium M (Not
> the P4M) family (or actually, the Yonah/Dotan and the future Merom CPUs)
> which doesn't have Hyper-threading support.
>
> http://www.theregister.co.uk/2005/08/23/intel_next_gen_architecture/
>The next generation Intel Pentium M "Merom" will not soppurt Hiperthreading, But it is not correct that Intel droped the idea. I know that the hyperthreading will come back in a more future CPU (one of the succesors of Merom), which will have 4 physical cores that can run 8 threads simultanously. Nir.
