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Date:      Fri, 04 Feb 2005 21:29:06 -0700
From:      Scott Long <scottl@freebsd.org>
To:        Astrodog <astrodog@gmail.com>
Cc:        Nathan Vidican <nvidican@wmptl.com>
Subject:   Re: Intel EMT64 Xeon vs AMD Opteron
Message-ID:  <42044B92.4040102@freebsd.org>
In-Reply-To: <2fd864e05020419434705bf70@mail.gmail.com>
References:  <000001c50a3c$50f2eba0$6800000a@r3140ca> <20050204103708.21608.qmail@web26801.mail.ukl.yahoo.com> <2fd864e05020419382a5e21b3@mail.gmail.com> <2fd864e05020419434705bf70@mail.gmail.com>

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Astrodog wrote:

> On Fri, 4 Feb 2005 19:38:43 -0800, Astrodog <astrodog@gmail.com> wrote:
> 
>>On Fri, 4 Feb 2005 11:37:08 +0100 (CET), Claus Guttesen
>><cguttesen@yahoo.dk> wrote:
>>
>>>>Cost wise, AMD Opteron 246 is roughly the same cost
>>>>as a 3.0Ghz Xeon ... But
>>>>how do they compare performance wise; specifically
>>>>related to FreeBSD?
>>>
>>>We have a dual xeon (nocona) @ 3.2 GHz and a dual
>>>opteron @ 2 GHz, both with 4 GB RAM and running the
>>>amd64-port. My impression is that the opteron performs
>>>*slightly* better than it's Intel-cousin.
>>>
>>>regards
>>>Claus
>>>
>>>_______________________________________________
>>>freebsd-amd64@freebsd.org mailing list
>>>http://lists.freebsd.org/mailman/listinfo/freebsd-amd64
>>>To unsubscribe, send any mail to "freebsd-amd64-unsubscribe@freebsd.org"
>>>
>>
>> From what I understand, EM64T is essentally an extention to x86, so
>>it will understand the AMD64 instructions, much the same way an
>>Athlon64 does. Opteron, once again, from what I've read on the topic
>>is "Actual" 64-bit, not an emulated version. Generally, I find Opteron
>>to be the best "Bang for your Buck", though what motherboard, and what
>>features you need there may also play a role there. AMD, so far, has
>>implied that the dual core opterons will be Socket 940, If that pans
>>out, the 940-based solution will be significantly more expandable,
>>since there's little to no chance of Intel continuing to use their
>>current Xeon socket when their Dual Core offerings come out, and I
>>suspect it would be technically impossible, given the Memory
>>Controller issues that its bound to create. Since AMD put the memory
>>controller on-die, they can resolve this issue in the core, and not
>>involve the chipsets of the motherboard itself.
>> Remember, Hyperthreading isn't dual core, its kinda like adding
>>another "Lane" to the processing pipeline of a single processor, so
>>that when something stalls, other things can still happen.
>> Hypertransport, on the other hand is AMD's method of connecting SMP
>>CPUs to eachother, memory, and devices on the motherboard.
>>
>>Sorry about the Hypertransport/Hyperthreading thing, but there seems
>>to be a great deal of confusion about what each are, and what's
>>good/bad about them, and they relate to the AMD/Intel decsion you're
>>making pretty explicitly.
>>
>>Personally, I say go with the Opteron. Worst case, performance and
>>reliability are the same, and you're supporting the underdog. Best
>>case, it blows your socks off, and in a year, you can go dual core.
>>Either way, you can't loose.
>>
>>---- Harrison Grundy
>>
> 
> 
> D'oh. One other thing. In the benchmarks I've seen, Opterons "Play
> Nicer" with SMP because of the Hypertransport setup in some
> applications. (IE, they don't fight over memory the way Xeons do).
> Look for a motherboard that uses a "4+4" or "4+2" memory configuration
> to take full advantage of this. (Differnt memory for each processor,
> kinda)

With FreeBSD, it's a bit of a toss-up.  There is no strong affinity
set or enforced between process memory and where the process is running.
Having some notion of affinity (i.e. NUMA support) would be a good
thing.  Oh, and the 4+2 configurations are typically pretty poor,
regardless.

Scott



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