AMD Opteron 2356 Quad-Core "Barcelona"

When looking at the AMD Phenom 9500 under Linux, we had found this processor had posed a number of issues from kernel panics to other troubles when running Ubuntu 7.10 with the Linux 2.6.22 kernel. Once, however, upgrading to Ubuntu 8.04 with the Linux 2.6.24 kernel these problems had vanished and we were pleased by this native quad-core desktop processor from AMD. Released a month prior to the first Phenom desktop CPUs were the quad-core Opteron 2300 "Barcelona" processors. We hadn't looked at any AMD Barcelona processors at that time, but today we finally have our hands on two of the new AMD Opteron 2356 server/workstation processors. The Opteron 2356 CPUs come clocked at 2.30GHz, and is a revision B3 Opteron meaning that it has a proper fix for the TLB erratum -- this model was introduced only earlier this month. We have benchmarked the new Opteron 2356 in both single and dual CPU configurations and have compared the results -- under Linux -- to two of Intel's quad-core Xeon processors.

Most of you should already know this, but these AMD quad-core processors just aren't two dual-core processors bridged together. Barcelona is a native quad-core processor design and each core has been improved since the Opteron 2200 series to offer improved performance per clock and greater bandwidth throughput, among many other improvements. Barcelona supports 3 bytes/cycle, which is double the instruction fetch bandwidth of the Intel Clovertown and older AMD Santa Rosa processors. The L2 cache is also tied into the northbridge at a rate of 128bits/cycle, which has also been doubled compared to earlier AMD processors. One of the other improvements for these processors is introducing 2MB of L3 cache, which is shared between the four processing cores. This in addition to each of the cores having 512KB of dedicated L2 cache. Intel's Harpertown has 12MB of L2 cache, but AMD is confident that their design is superior. As would be expected with virtualization being the latest buzz word, the Opteron 2300 processors continue to support AMD's hardware-based virtualization technology (AMD-V) as well as Rapid Virtualization Indexing, which allows virtual machines to directly manage memory. Other features include AMD Memory Optimizer Technology, Hyper Transport 3.0, Balanced Smart Cache, Wide Floating-Point Accelerator, and Common Core Strategy.

Like the AMD Phenom desktop series, the Opteron 2300 series also supports Independent Dynamic Core Technology and Dual Dynamic Power Management along with the CnQ-like PowerNow! Technology. These new power-saving technologies allow the four cores to operate at different frequencies depending upon the load of each core thereby conserving power and reducing the heat output as all of the cores are not bound to a single, shared operating frequency. The Dual Dynamic Power Management (DDPM) reduces power consumption with PowerNow and allows per-processor power management. The ACP consumption for the Opteron 2356 is 75 Watts and is the same as all of the current Opteron 23XX CPUs. Note that the 75 Watts measurement is AMD's new metric, Average CPU Power (ACP), which they claim to be more accurate than TDP (Thermal Design Power). The Barcelona processors are built on a 65nm SOI process and do support SSE4a.

Aside from the Opteron 2356, the other newest Barcelona processors released this month include the Opteron 2352, 2354, 2358 SE, and 2360 SE (new processors in the 8300 series have also been released). They run at 2.1GHz, 2.2GHz, 2.4GHz, and 2.5GHz, respectively. All share a 75W ACP aside from the "SE" variants that are running warmer at 105W. A single Opteron 2350 starts out at $250 USD while one Opteron 2356 will set you back about $670 USD. As was mentioned in the introduction, these new Opteron processors are revision B3 and free of the notorious TLB erratum bug.