Here is all the replies I got. Thanks for all the info.
-Patrick
pchapin_at_twilight.vtc.vsc.edu
The Alpha has a 64 bit data path and 64 bit registers. All 64 bit
operations are done in one "step." In fact, 32 bit data objects are read
from memory and extended to 64 bits inside the registers before they are
used. (This extension operation requires no additional time).
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VGOKHALE_at_us.oracle.com
That's absolutely bogus... all Alpha CPUs will load 64bit (quadword as they
call it) in one instruction. This is the way it has been even before Sun ever
came up with their first 64bit SPARC CPUs. Things get even better if you're
using latest EV6 Alpha CPUs. It has 4 integer units compared to 2 in the older
EV56 processor, plus it executes instructions out-of-order. Net result is you
get atleast 1.5X or better performance of an EV56 Alpha processor for same (or
slightly LOWER) clock speed. Current SPARC processors are far behind in
performance wrt what EV6 can do.
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aad_at_nw.verio.net
One has to examine the architectures at higher granularities to make
that sort of judgement. For example, if a given UltraSPARC chip takes
two instructions to load a 64 bit word, perhaps there are multiple
execution units that can load them in ||, or perhaps those loads are
pipelined, interleaved, or overlapped.
There's also the fact that the Alpha's clock rates tend to be somewhat
higher, and in the end it's how the system as a whole, including the
off-chip memory system, performs -- when running a given application.
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grant_at_storm.com
I'm not sure, but I think your correct. 2 operations vs 1 op. But, this
doesn't in any way mean that the Sun is twice as fast as the Alpha. There
lots and lots of other things that contribute to this. The is no basis for
comparson at that level.
Though, in my opinion. I believe the UltraSparc serios of chips(Sun) to be
more efficent and quick than the latest Alpha series. Both are rather fine
CPU's.
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francini_at_progress.com
Your coworker has a serious case of Sun-stroke (a disease where Sun can do
no wrong, and the afflicted person simply absorbs all of Sun's FUD at face
value).
Loading, storing, and manipulating 64-bit quantities on Alpha processors
is, of course, done in a single operation.
Instructions like LDQ, STQ, etc. do direct "quadword" manipulation.
(Quadword is DECspeak for 4 16-byte quantities. A word is 16 bits.
Now, some code may cause the compiler to generate LDL/STL (Load
Longword/Store Longword) instructions, which manipulate 32-bit quantities.
But generally, when you're dealing with "native" datatypes (64-bit
integters and the like), they're loaded and stored in a SINGLE instruction.
My reference is the Alpha Architecture Handbook, the most recent version of
which is available via Amazon.com at
http://www.amazon.com/exec/obidos/ASIN/1555582028/o/qid=924288413/sr=2-1/002-845
3797-3054069
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jharvey_at_eccnet.eccnet.com
You really need to know exactly what the context is here. What is ment by
an operation?
The alpha chip typically loads in a 64byte block with each fetch from
memory to cache.
> That would lead me to believe that a Sun is twice as fast as an Alpha.
>
> Is this true?
>
Not if validated benchmarks mean anything.
> There has been a rather heated discussion around about which is better.
>
If raw performance is the issue. Alpha wins.
If scalability is the issue. alpha wins.
If application availability is the issue....... NT on Intel (sadly enough)
wins.
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bingwersen_at_traverse.com
Let us keep in mind, how long sun has had a 64bit paltform available!
compared to the Alpha.....
And how do we know that the alpha 2 step process is actually slower than
Sun's 1 step....mabey sun just has a longer stride....
It all really depends on the money you want to spend and the applications
you are
using!
Alpha has always won the price/performance & scalability awards!
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LARRY.CLEGG_at_LPL.COM
Please...Sun twice as fast...that's ludicrous....
Take a look at this performance chart....look around on the web at places
like Gartner Group, etc. and you'll see the same thing from independent
testers.
http://www.digital.com/alphaserver/performance/sum/
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bseymour_at_ns.encore.com
Which Sun? Only the recent (Ultra?) are 64 bit processors, and Solaris 7
is the first version that is a 64 bit OS.
Load? Be more specific. From memory to a register on an Alpha, assuming
proper memory alignment, is one assembly language instruction. Now, that
said, where is the data? In cache? Which one? In main memory? Paged out?
Is the TLB entry active? This is not a simple question, apart the
basic, one load instruction will load a 64 bit value into a register.
That's the short version. You'll probably get a bunch of detail from
others. We have both Alpha and Ultra Sparc machines in house
and they are both fast and reliable. So far I don't have a feeling
for one being better than the other, just different.
Received on Fri Apr 16 1999 - 21:01:03 NZST