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AMD "Barcelona" die shot (Source: AMD)

SPECfp_rate2006 performance (Source: AMD)

SPECint_rate2006 performance (Source: AMD)
AMD showcases a 2.6 GHz simulated "Barcelona" -- and everyone has something to say about it

As more details of AMD Barcelona continue to trickle out, I had the opportunity to discuss some of the newest benchmarks with a few analysts.

Just a few weeks ago, AMD's website unveiled specific SPEC benchmarks claims.  A footnote to the benchmarks claims the following:
The comparison presented above is based on the best performing x86 Dual-CPU Dual-Core configurations with the Xeon 5160 and AMD Opteron processor Model 2222 SE, and Dual-CPU Quad-Core configurations with Xeon 5355.  Dual-CPU Quad-Core AMD Opteron processor estimates based on internal AMD simulations at 2.6GHz.
For reference, the Intel Xeon 5355 is clocked at 2.66 GHz and is priced around $1,600.  The Intel Xeon 5160 has a core frequency of 3.0 GHz and runs approximately $850.  AMD's 3.0 GHz Opteron 2222 SE runs just under $1,000 at retail.

AMD guidance puts the SPECint_rate performance of two quad-core 2.6 GHz Barcelona approximately 23% higher than the quad-core 2.66 GHz Xeon 5355; a score of approximately 104 versus 84.8.  SPECfp_rate performance puts the Barcelona performance almost 58% higher than that of the Intel Xeon 5355; 92 versus 58.8.  Seperate AMD documentation puts these figures at 21% and 50%, respectively.

In January of this year AMD corporate vice president for server and workstation products, Randy Allen, boldly stated, "We expect across a wide variety of workloads for Barcelona to outperform Clovertown by 40 percent."  That 40%, it would appear, is potentially in-line with figure proposed by the SPECfp_rate benchmark.

Industry analyst, David Kanter, tells DailyTech, "Historically high performance computing is the greatest strength for AMD."  He clarifies, "For HPC, AMD is going to wipe the floor with Intel."

Barcelona HPC improvements include a wider instruction set, L3 cache, new SIMD support and better branch prediction.  Kanter also claims, "Improvements that Barcelona is making are not necessarily as targeted for single threaded performance." Specifically, Kanter discounts SSE improvements as a major performance head turner, but for some applications it certainly is a huge single threaded help.  For example, it's not going to make web browsers or word processors faster; but it would certainly help single threaded performance for games and numerical stuff.

AnandTech founder Anand Lal Shimpi disagrees on Kanter's dismissal of new SSE instructions on Barcelona.  "Many of the major changes to Barcelona were driven by one significant change: what AMD is calling SSE128," he states.  Shimpi tells DailyTech, "The culmination of the SSE128 improvements is very similar to some of the changes made in the Yonah to Merom transition."

However, what the SPECint_rate and SPECfp_rate benchmarks don't show is the ability to handle process-to-process throughput rates.  Kanter highlights this to DailyTech, stating, "For stuff like web serving, application serving, I think Barcelona will kinda be a mixed bag, won't be a real home run."  He clarifies this by emphasizing many of the K10 changes have possible drawbacks, including the split power-plane. 

"The split power-plane, while saving power, has tendencies to make moving data between them a little awkward." Kanter continues, "It's a subtle thing, but in the end it will all depend on latency."

On the other hand, changes to the architecture are actually specifically geared at improving socket-to-socket performance.  Four socket systems will now utilize one 16-bit HyperTransport link to each socket on the system -- eight-socket systems will utilize one 8-bit HyperTransport link to each socket.  But, as Kanter stated earlier, this is largely an HPC change and will not affect desktop and dual-socket performance.

Ars Technica's Jon Stokes puts it the most succinctly, "If I could sum up Barcelona's substantial changes to the K8 core in one phrase, it would be: Barcelona makes better use of system bandwidth."

While Stokes, Kanter and Shimpi all allude to stronger single-core performance from Intel's Core architecture, Shimpi doesn't rule out Barcelona on the desktop just yet. "Barcelona will be a success for AMD; the long awaited architectural update to K8 should yield significant performance improvements, especially in current areas of weakness for the K8 (e.g. video encoding)," he claims.

However, there is still a lot unsaid even this late in the game.  While AMD's multi-core SPEC guidance claims the simulation runs on a 2.6 GHz Barcelona processor, guidance from the company as late as last month states the fastest debut K10 cores will top out at 2.3 GHz.

Kanter closes, "Given the evidence I saw at ISSCC 2007, I'm pretty confident the chip can make it to 2.8 GHz."


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RE: 40%
By FITCamaro on 6/4/2007 1:18:10 PM , Rating: 1
One place the current C2D fails is on the highend. To get dual 16x lanes with SLI right now, you have to buy a 680i motherboard which is a minimum of $200. Average board price is like $250. To get a crossfire board is far cheaper.


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