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Cache prefetching can be accomplished either by hardware or by software. [3]Hardware based prefetching is typically accomplished by having a dedicated hardware mechanism in the processor that watches the stream of instructions or data being requested by the executing program, recognizes the next few elements that the program might need based on this stream and prefetches into the processor's ...
Fetching the instruction opcodes from program memory well in advance is known as prefetching and it is served by using a prefetch input queue (PIQ). The pre-fetched instructions are stored in a queue. The fetching of opcodes well in advance, prior to their need for execution, increases the overall efficiency of the processor boosting its speed ...
When a next-line predictor points to aligned groups of 2, 4, or 8 instructions, the branch target will usually not be the first instruction fetched, and so the initial instructions fetched are wasted. Assuming for simplicity, a uniform distribution of branch targets, 0.5, 1.5, and 3.5 instructions fetched are discarded, respectively.
Prefetching in computer science is a technique for speeding up fetch operations by beginning a fetch operation whose result is expected to be needed soon. Usually this is before it is known to be needed, so there is a risk of wasting time by prefetching data that will not be used. The technique can be applied in several circumstances:
In computer engineering, instruction pipelining is a technique for implementing instruction-level parallelism within a single processor. Pipelining attempts to keep every part of the processor busy with some instruction by dividing incoming instructions into a series of sequential steps (the eponymous "pipeline") performed by different processor units with different parts of instructions ...
Runahead is a technique that allows a computer processor to speculatively pre-process instructions during cache miss cycles. The pre-processed instructions are used to generate instruction and data stream prefetches by executing instructions leading to cache misses (typically called long latency loads) before they would normally occur, effectively hiding memory latency.
64-bit, integrated memory controller, 16 byte instruction prefetching AMD K10: 2007 Superscalar, out-of-order execution, 32-way set associative L3 victim cache, 32-byte instruction prefetching: ARM7TDMI (-S) 2001 3 ARM7EJ-S: 2001 5 ARM810 5 static branch prediction, double-bandwidth memory ARM9TDMI 1998 5 ARM1020E 6 XScale PXA210/PXA250: 2002 7 ...
Hardware scout is a technique that uses otherwise idle processor execution resources to perform prefetching during cache misses. When a thread is stalled by a cache miss, the processor pipeline checkpoints the register file, switches to runahead mode, and continues to issue instructions from the thread that is waiting for memory.