[理工] [計組] pipeline 的執行時間算法
Consider a MIPS machine with a 5-stage pipeline with a cycle time of 10ns.
Assume that you are executing a program where a fraction,f,of all instructions
immediately follow a load upon which they are dependent.
(2)Consider a scenario where the MEM stage, along with its pipeline registers,
needs 12 ns. There are now two options: add another MEM stage so that
there are MEM1 and MEM2 stages or increase the cycle time to 12 ns so that
the MEM stage fits within the new cycle time and the number of pipeline
stages remain unaffected. For a program mix with the above characteristics,
when is the first option better than the second. Your answer should be based
on the value of f.
解答:Option1:Time1 = [ (6-1) + N + 2*N*f ]*10 ns
~~~~~~~~~~~~~~~~~~~~~
這應該是clock cycles對吧?
我想問這 (6-1) cycles 是從哪理來的?
還有為什麼多了一個MEM階段後 要比 5-stage pipeline 多 stall N*f cycles?
我想破頭還是不知道 請各位版友告訴我吧 感謝~
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10/11 20:48, , 1F
10/11 20:48, 1F
※ 編輯: lexa 來自: 27.105.7.134 (10/12 02:38)
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