How Many Processor Cores Are Enough?
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From: ranjit_mathews@yahoo.com on 9 Oct 2006 19:59 Greg Lindahl wrote: > In article <1160421201.367674.89490(a)c28g2000cwb.googlegroups.com>, > ranjit_mathews(a)yahoo.com <ranjit_mathews(a)yahoo.com> wrote: > > >> Spec/GHz is very nearly totally meaningless. > > > >Then why does the Core 2 Duo find favor over Pressler core processors? > > Because Core2 is faster at lower power? Note that "GHz" doesn't appear > in the sentence; Ghz is just an implementation detail, not comparable > between designs. No, since for a given design, if you know ops/GHz, you can estimate what the ops would be at (say) 50% more GHz. > But "faster" and "lower power", those are comparable. > > -- greg
From: Bill Todd on 9 Oct 2006 20:20 ranjit_mathews(a)yahoo.com wrote: > Greg Lindahl wrote: >> In article <1160421201.367674.89490(a)c28g2000cwb.googlegroups.com>, >> ranjit_mathews(a)yahoo.com <ranjit_mathews(a)yahoo.com> wrote: >> >>>> Spec/GHz is very nearly totally meaningless. >>> Then why does the Core 2 Duo find favor over Pressler core processors? >> Because Core2 is faster at lower power? Note that "GHz" doesn't appear >> in the sentence; Ghz is just an implementation detail, not comparable >> between designs. > > No, since for a given design, if you know ops/GHz, you can estimate > what the ops would be at (say) 50% more GHz. And what, exactly, do you believe you have gained once you've done that? - bill
From: Greg Lindahl on 9 Oct 2006 21:00 In article <1160438357.807739.92810(a)b28g2000cwb.googlegroups.com>, ranjit_mathews(a)yahoo.com <ranjit_mathews(a)yahoo.com> wrote: >> >Then why does the Core 2 Duo find favor over Pressler core processors? >> >> Because Core2 is faster at lower power? Note that "GHz" doesn't appear >> in the sentence; Ghz is just an implementation detail, not comparable >> between designs. > >No, since for a given design, if you know ops/GHz, you can estimate >what the ops would be at (say) 50% more GHz. Core 2 Duo and Pressler are different designs. I'm mystified as to what we're discussing. -- g
From: ranjit_mathews@yahoo.com on 9 Oct 2006 21:25 Bill Todd wrote: > ranjit_mathews(a)yahoo.com wrote: > > Greg Lindahl wrote: > >> In article <1160421201.367674.89490(a)c28g2000cwb.googlegroups.com>, > >> ranjit_mathews(a)yahoo.com <ranjit_mathews(a)yahoo.com> wrote: > >> > >>>> Spec/GHz is very nearly totally meaningless. > >>> Then why does the Core 2 Duo find favor over Pressler core processors? > >> Because Core2 is faster at lower power? Note that "GHz" doesn't appear > >> in the sentence; Ghz is just an implementation detail, not comparable > >> between designs. > > > > No, since for a given design, if you know ops/GHz, you can estimate > > what the ops would be at (say) 50% more GHz. > > And what, exactly, do you believe you have gained once you've done that? If you can estimate how much faster they can clock it relative to how much faster other processors can be clocked, you can estimate how much faster it will get relative to other processors.
From: Bill Todd on 10 Oct 2006 00:10
ranjit_mathews(a)yahoo.com wrote: > Bill Todd wrote: >> ranjit_mathews(a)yahoo.com wrote: >>> Greg Lindahl wrote: >>>> In article <1160421201.367674.89490(a)c28g2000cwb.googlegroups.com>, >>>> ranjit_mathews(a)yahoo.com <ranjit_mathews(a)yahoo.com> wrote: >>>> >>>>>> Spec/GHz is very nearly totally meaningless. >>>>> Then why does the Core 2 Duo find favor over Pressler core processors? >>>> Because Core2 is faster at lower power? Note that "GHz" doesn't appear >>>> in the sentence; Ghz is just an implementation detail, not comparable >>>> between designs. >>> No, since for a given design, if you know ops/GHz, you can estimate >>> what the ops would be at (say) 50% more GHz. >> And what, exactly, do you believe you have gained once you've done that? > > If you can estimate how much faster they can clock it relative to how > much faster other processors can be clocked, you can estimate how much > faster it will get relative to other processors. That, as the saying goes, is a mighty big 'if'. On what basis would you estimate how much faster those processors can clock, anyway? It's certainly not simply a matter of GHz, since in a given process different processor designs have wildly different maximum clock rates (depending, of course, on the complexity of the slowest of their pipeline stages, among other things). Or, if your suggestion is that you can estimate how much faster (percentage-wise) a processor would be in a subsequent process generation, that estimate would seem to be be largely independent of clock rate (assuming the design were clocked to its limit in both cases). I'm still looking for a specific example of how performance/GHz is useful: if you think you've already provided one, you think incorrectly (at least until you explain your contention about the specific relevance of performance/GHz much more clearly than you yet have). - bill |