PCTuning fórum

Highlights on the execution pipelines:

4-way microarchitecture design
Integer core has two EX and two AGLU pipelines, plus an LSU (2.10.2)
Floating-point unit (FPU) has two FMAC and two IMMX pipelines (2.11)

Up to 4 macro-ops per clock cycle can be issued from the (shared) frontend to either of the two cores. Within each core, up to 4 macro-ops per clock cycle can be sent to an integer or the floating-point scheduler.

The integer scheduler can dispatch up to 4 micro-ops per cycle, one to each of the 4 pipelines. Almost all ALU operations are handled by the 2 EX pipelines, except some LEA instructions which also utilize AGU. Thus the integer core can execute only up to 2 x86 instructions per clock cycle, resulting in a maximum integer IPC of 2.0 (in units of x86 instructions). Note however this estimate does not include the computing throughput of the integer SIMD pipelines in the FPU.

The FPU scheduler can dispatch up to four 128-bit operations with the following combinations: (1) any of {FMUL, FADD, FMAC, FCVT, IMAC}; and (2) any of {FMUL, FADD, FMAC, Shuffle, Permute}; and (3) any of {AVX, MMX, ISSE}; and (4) any of {AVX, MMX, ISSE, FSTORE}.

From a layman's viewpoint, the shared FPU seems to offer only half the throughput of two K10 cores for independent FMUL and FADD operations. However, in previous Opteron, vectorized loads and stores also share the FMUL and FADD pipelines; in Bulldozer, vectorized loads are either "free" or handled by the IMMX pipelines. Note that when FPU is throughput bottleneck, each arithmetic operation should be paired with on average one load or store. A perhaps more significant overhead saving comes from various vectorized register moves which can now be dispatched concurrently to separate IMMX pipelines. Thus the shared FPU in Bulldozer is actually a very balanced design.

flanker píše:v těch hrách je to jasné, jsou to vysoká herní rozlišení...Chtělo by to spíš nějaké méněvláknové operace, více programů. Možná že leccos už taky polepšil mírně updatovaný BIOS.

we're almost-shockingly left without an AMD CPU to recommend at any price point.