Bulldozer for Servers: Testing AMD's "Interlagos" Opteron 6200 Seriesby Johan De Gelas on November 15, 2011 5:09 PM EST
Introducing AMD's Opteron 6200 Series
When virtualization started to get popular (ca. 2005-2007), there was a fear that this might slow the server market down. Now several years later, the server market has rarely disappointed and continues to grow. For example, IDC reported a 12% increase in revenue when comparing Q1 2010 and Q1 2011. The server market in total accounted for $12 billion revenue and almost two million shipments in Q1 2011, and while the best desktop CPUs generally sell for $300, server chips typically start at $500 and can reach prices of over $3000. With the high-end desktop market shrinking to become a niche for hardcore enthusiasts--helped by the fact that moderate systems from several years back continue to run most tasks well--the enterprise market is very attractive.
Unfortunately for AMD, their share of the lucrative server market has fallen to a very low percentage (4.9%) according IDC's report early this year (some report 6-7%). It is time for something new and better from AMD, and it seems that the Bulldozer architecture is AMD's most server-centric CPU architecture ever. We quote Chuck Moore, Chief Architect AMD:
By having the shared architecture, reducing the size and sharing things that aren’t commonly used in their peak capacity in server workloads, “Bulldozer” is actually very well aligned with server workloads now and on into the future. In fact, a great deal of the trade-offs in Bulldozer were made on behalf of servers, and not just one type of workload, but a diversity of workloads.
This alginment with server workloads can also be found in the specs:
|L1 Instructions||8x 64 KB 2-way||12x 64 KB 2-way||6x 32 KB 4-way|
|L1 Data||16x 16 KB 4-way||12x 64 KB 2-way||6x 32 KB 4-way|
|L2 Cache||4x 2MB||12x 0.5MB||6x 256 KB|
|L3 Cache||2x 8MB||2x 6MB||12MB|
|IMC Clock Speed||2GHz||1.8GHz||2GHz|
|Interconnect||4x HT 3.1 (6.4 GT/s)||4x HT 3.1 (6.4 GT/s)||2x QPI (4.8-6.4 GT/s)|
The new Opteron has loads of cache, faster access to memory and more threads than ever. Of course, a good product is more than a well designed microarchitecture with impressive specs on paper. The actual SKUs have to be attractively priced, reach decent clock speeds, and above all offer a good performance/watt ratio. Let us take a look at AMD's newest Opterons and how they are positioned versus Intel's competing Xeons.
|AMD vs. Intel 2-socket SKU Comparison|
|High Performance||High Performance|
|High clock / budget||High clock / budget|
|Power Optimized||Power Optimized|
The specifications (16 threads, 32MB of cache) and AMD's promises that Interlagos would outperform Magny-cours by a large margin created the impression that the Interlagos Opteron would give the current top Xeons a hard time. However, the newest Opteron cannot reach higher clock speeds than the current Opteron (6276 at 2.3GHz), and AMD positions the Opteron 6276 2.3GHz as an alternative to the Xeon E5649 at 2.53GHz. As the latter has a lower TDP, it is clear that the newest Opteron has to outperform this Xeon by a decent margin. In fact most server buyers expect a price/performance bonus from AMD, so the Opteron 6276 needs to perform roughly at the level of the X5650 to gain the interest of IT customers.
Judging from the current positioning, the high-end is a lost cause for now. First, AMD needs a 140W TDP chip to compete with the slower parts of Intel's high-end armada. Second, Sandy Bridge EP is coming out in the next quarter--we've already seen the desktop Sandy Bridge-E launch, and adding two more cores (four more threads) for the server version will only increase the performance potential. The Sandy Bridge cores have proven to be faster than Westmere cores, and the new Xeon E5 will have eight of them. Clock speeds will be a bit lower (2.0-2.5GHz), but we can safely assume that the new Xeon E5 will outperform its older brother by a noticeable margin and make it even harder for the new Opteron to compete in the higher end of the 2P market.
At the low-end, we see some interesting offerings from AMD. Our impression is that the 6212 at 2.6-2.9GHz is very likely to offer a better performance per dollar ratio than the low-end Xeons E560x that lack Hyper-Threading and turbo support.
Okay, we've done enough analyzing of paper specs; let's get to the hardware and the benchmarks. Before we do that, we'll elaborate a bit on what a server centric architecture should look like. What makes server applications tick?