Tim said:
How do I tell a "new" P4 from an old one when I go shopping?
Simple answer: Look for HyperThreading.
Complicated answer: The answer changed today, with the release of the
first of the Prescott cored P4s, designated P4 x.xE. Northwood was the
most recent P4 core on the market yesterday. Prescott is built with a
90nm process (Northwood is 130nm), has double the on-chip cache and
some new instructions (SSE3). Confusing matters still further the
fastest Prescott-cored P4s haven't been released yet, so the
top-of-the-range 3.4GHz P4 EE (Extreme Edition, with more on-chip
cache [good for spice], basically a rebadged Xeon) is still based on
the Northwood core.
Tim
Hi Tim,
You mentioned that the additional cache memory would improve things for
spice. Why is that? Would that help a pentium in the sense that its
floating point operations seem to be the thing that slow it down the
most (from what I understand) in a spice simulation.
Here's some verbiage I got from another newsgroup about floating point
math and the P4:
|The P4 is pretty much a wimp on everything fp, except vectorized,
|straightforward mul, add, sub, using SSE2.
|A lot of time consuming work like matrix/tensor multiplications,
|transformations etc. does fall into that category though. So it might
|be a good idea, to see to it, that the code is compiled with Intels
|auto vectorizing optimizing compiler.
|If everything is optimal, you can get 3-3.5 times the performance on
|single precision fp (this is the kind of performance you see in P4
|video encoding). On the other hand, branches, division, ruin it all.
|Just reading some single benchmark, is not going to be of any use to
|you. P4/Xeon benchmarks tend to be 100% SSE2, outrageously optimized
|and highly flattering for Intel. Real applications might be a
|different thing (scalar '387?). Unless you know what the code looks
|like, and how it is compiled, you cannot be sure to get the
|performance common benchmarks imply.
|If you write the software yourself, Intels compiler is a free
|download. Try it if you haven't already.
I may just go out and rent an Athlon for a day and do a spice test run.
P.