rather unfortunate article on Mac
Bari Ari
bari at onelabs.com
Thu Jan 31 21:32:43 PST 2002
Art Edwards wrote:
>On Thu, Jan 31, 2002 at 08:48:11PM -0600, Bari Ari wrote:
>
>>We looked at building some very dense clusters using the G4s. The
>>floating point performance is great (15Gflops peak) as well as the raw
>>performance vs. power consumption (21watts at 1GHz). The main drawbacks are
>>price of the CPUs (though the new 7455s are only $125/10k for the 800MHz
>>versions), lack of support from Motorola and lack of any decent
>>clustering software such as Scyld.
>>
>
>Is it still true that the vector processors only handle single precision
>floating point?
>
I don't really follow them too closely anymore, but a quick check of the
datasheet mentions:
MPC7455 and MPC7445 microprocessors feature a high-frequency superscalar
G4 core capable of issuing four instructions per clock cycle (three
instructions + branch) into eleven independent execution units:
* Four integer units (3 simple + 1 complex)
* Double-precision floating-point unit
* Four AltiVec units (simple, complex, floating, and permute)
* Load/store unit
* Branch processing unit
AltiVec technology operations are performed on multiple data elements by
a single instruction. This is
often referred to as SIMD (single instructions, multiple data) parallel
processing. AltiVec technology offers
support for:
16-way parallelism for 8-bit signed and unsigned integers and characters
8-way parallelism for 16-bit signed and unsigned integers
4-way parallelism for 32-bit signed and unsigned integers and IEEE
floating point numbers
Bari
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