Features 64-bit x86-based microprocessor On chip double-data-rate (DDR) memory controller [low memory latency] Three HyperTransport links [connect to other devices without support chips] Out of order, superscalar processor Adds 64-bit (48-bit virtual and 40-bit physical) addressing and expands number of registers Supports legacy 32-bit applications without modifications or recompilation
Features Double the number of registers Integer general purposes registers (GPR’s) – 16 each Streaming SIMD extension (SSE) registers – 16 each Satisfies the register allocation needs of more than 80% of functions appearing in a typical program. Connected to a memory through an integrated memory controller High performance I/O subsystem via HyperTransport bus.
Microarchitecture Works with fixed-length micro-ops and dispatches into two independent schedulers: One for integer, and one for floating point and multimedia (MMX, 3DNow, SSE and SSE2) Load and store micro-ops go to the load/store unit 11 micro-ops each cycle to the following execution resources. Three integer execution units Three address generation units Three floating point and multimedia units Two load/store to the data cache
Pipeline Long enough for high frequency and short enough for good IPC (Instructions per cycle) Fully integrated from instruction fetch through DRAM access. Execute pipeline is typically 12 stages for integer 17 stages for floating-point Data cache access occurs in stage 11. In case that L1 cache miss, the pipeline access the L2 cache in parallel and the request goes to the system request queue. Pipeline in the DRAM run as the same frequency as the core
Memory, Cache, and HyperTransport
Cache Separate L1 Instruction and Data caches. Each is 64 Kbytes, 2-way set associative, 64-byte cache line. L2 cache (Data & Instructions) Size: 1 Mbytes. 16-way set associative. uses a pseudo-least-recently-used (LRU) replacement policy Independent L1 and L2 translation look-aside buffers (TLB). The L1 TLB is fully associative and stores thirty-two 4-Kbyte page translations, and eight 2-Mbyte/4-Mbyte page translations. The L2 TLB is four-way set-associative with Kbyte entries.
Onboard Memory Control 128-bit memory bus Latency reduced and bandwidth doubled Multicore: Processors have own memory interface and own memory Available memory scales with the number of processors DDR-SDRAM only Up to 8 registered DDR DIMMs per processor Memory bandwidth of up to 5.3 Gbytes/s per processor.
HyperTransport Bidirectional, serial/parallel, scalable, high-bandwidth low- latency bus Packet based 32-bit words regardless of physical width Facilitates power management and low latencies
HyperTransport in the Opteron 16 CAD HyperTransport (16-bit wide, CAD=Command, Address, Data) processor-to-processor and processor-to-chipset bandwidth of up to 6.4 GB/s (per HT port) 8-bit wide HyperTransport for components such as normal I/O-Hubs
InterCPU Connections Multiple CPUs connected through a proprietary extension running on additional HyperTransport interfaces Allows support of a cache-coherent, Non-Uniform Memory Access, multi-CPU memory access protocol Non-Uniform Memory Access Separate cache memory for each processor Memory access time depends on memory location. (i.e. local faster than non-local) Cache coherence Integrity of data stored in local caches of a shared resource Each CPU can access the main memory of another processor, transparent to the programmer