Thus page only partly updated for quad-core.

The processors in Louhi are quad-core AMD Opteron (Barcelona or AMD Family 10h) processors running at 2.3 GHz. They comprise of several components, four cores with individual L1 and L2 caches, an integrated memory controller and three coherent HyperTransport links. A crossbar switch links the components together.

Core

Opteron supports both 64-bit x86-64 instructions, as well as legacy x86 instructions. In addition, it supports several important extensions:  SSE, SSE2, SSE3, SSE4A, MMX and 3DNow!, enhanced 3dNOW!, ABM and 64-bit instruction set extensions. In numerical code SSE and SSE2 are of great importance in order to achieve good performance. Each core has an SSE2 functional unit that can calculate two 64-bit floating-point results per clock giving a theoretical maximum throughput of 10.4 GF/s per processor.

Cache

Each core has two 64 KB L1 caches: one instruction cache and one data cache. The L1 data cache has a 3-cycle latency and supports two 64-bit operations per cycle.  In addition, each core has a 1 MB L2 cache with a latency of 11 cycles. The cache architecture is exclusive, data in L1 is not duplicated in L2.

Memory

Compute nodes have 2 GB of DDR2-800 ECC memory in a dual-channel configuration. This gives each node 1 GB of memory per core with a peak transfer rate of 5.3 GB/s. The service nodes have 4 GB of memory per core.