現(xiàn)代計(jì)算機(jī)體系結(jié)構(gòu)-wenkub
2022-08-17 03:08:20 本頁面
【正文】 Op Queue If reservation station free (no structural hazard), control issues instr amp。 between 2 times, the instruction is in execution ? When and Where in a pipeline? ? Note: Dynamic execution creates WAR and WAW hazards and makes exceptions harder ? Why it can create WAR and WAW? 2022/8/17 8 Dynamic Scheduling Step 1 ? Simple pipeline had 1 stage to check both structural and data hazards: Instruction Decode (ID), also called Instruction Issue ? Split the ID pipe stage of simple 5stage pipeline into 2 stages: ? Issue— Decode instructions, check for structural hazards ? Read operands— Wait until no data hazards, then read operands ? Understand? Ex IS Ex Wb 2022/8/17 9 A Dynamic Algorithm: Tomasulo’s ? For IBM 360/91 (before caches!) –? Long memory latency ? Goal: High Performance without special pilers ? Small number of floating point registers (4 in 360) prevented interesting piler scheduling of operations –This led Tomasulo to try to figure out how to get more effective registers — renaming in hardware! ? Why Study 1966 Computer? ? The descendants of this have flourished! –Alpha 21264, Pentium 4, AMD Opteron, Power 5, … 2022/8/17 10 Tomasulo Algorithm ? Control amp。 buffers distributed with Function Units (FU) –FU buffers called ―reservation stations‖。 sends operands (renames registers). 2. Execute—operate on operands (EX) When both operands ready then execute。 –40 clocks for Flopt. / 2022/8/17 16 Tomasulo Example I ns tr uc ti on s tat us : E xec W r i t eIns t ruc t i on j k Is s u e Co m p R es u l t Bu s y A d d res sLD F6 34+ R2 L oa d1 NoLD F2 45+ R3 L oa d2 NoM U L T D F0 F2 F4 L oa d3 NoS U BD F8 F6 F2D IV D F 10 F0 F6ADDD F6 F8 F2R e s e r v ati on Stat ions : S1 S2 RS RST i m e Nam e Busy Op Vj Vk Qj QkA dd1 NoA dd2 NoA dd3 NoM ul t 1 NoM ul t 2 NoR e gis te r r e s ult s tat us :C loc k F0 F2 F4 F6 F8 F 10 F 12 ... F 300 FUClock cycle counter FU count down Instruction stream 3 Load/Buffers 3 FP Adder . 2 FP Mult . 2022/8/17 17 Tomasulo Example Cycle 1 I ns tr uc ti on s tat us : E xec W r i t eIns t ruc t i on j k Is s u e Co m p R es u l t Bu s y A d d res sLD F6 34+ R2 1 L oa d1 Y e s 34+ R2LD F2 45+ R3 L oa d2 NoM U L T D F0 F2 F4 L oa d3 NoS U BD F8 F6 F2D IV D F 10 F0 F6ADDD F6 F8 F2R e s e r v ati on Stat ions : S1 S2 RS RST i m e Nam e Busy Op Vj Vk Qj QkA dd1 NoA dd2 NoA dd3 NoM ul t 1 NoM ul t 2 NoR e gis te r r e s ult s tat us :C loc k F0 F2 F4 F6 F8 F 10 F 12 ... F 301 FU L oa d12022/8/17 18 Tomasulo Example Cycle 2 I ns tr uc ti on s tat us : E xec W r i t eIns t ruc t i on j k Is s u e Co m p R es u l t Bu s y A d d res sLD F6 34+ R2 1 L oa d1 Y e s 34+ R2LD F2 45+ R3 2 L oa d2 Y e s 45+ R3M U L T D F0 F2 F4 L oa d3 NoS U BD F8 F6 F2D IV D F 10 F0 F6ADDD F6 F8 F2R e s e r v ati on Stat ions : S1 S2 RS RST i m e Nam e Busy Op Vj Vk Qj QkA dd1 NoA dd2 NoA dd3 NoM ul t 1 NoM ul t 2 NoR e gis te r r e s ult s tat us :C loc k F0 F2 F4 F6 F8 F 10 F 12 ... F 302 FU L oa d2 L oa d1Note: Can have multiple loads outstanding 2022/8/17 19 Tomasulo Example Cycle 3 I ns tr uc ti on s tat us : E xec W r i t eIns t ruc t i on j k Is s u e Co m p R es u l t Bu s y A d d res sLD F6 34+ R2 1 3 L oa d1 Y e s 34+ R2LD F2 45+ R3 2 L oa d2 Y e s 45+ R3M U L T D F0 F2 F4 3 L oa d3 NoS U BD F8 F6 F2D IV D F 10 F0 F6ADDD F6 F8 F2R e s e r v ati on Stat ions : S1 S2 RS RST i m e Nam e Busy Op Vj Vk Qj QkA dd1 NoA dd2 NoA dd3 NoM ul t 1 Y e s M U L T D R(F 4) L oa d2M ul t 2 NoR e gis te r r e s ult s tat us :C loc k F0 F2 F4 F6 F8 F 10 F 12 ... F 303 FU M ul t 1 L oa d2 L oa d1? Note: registers names are removed (“renamed”) in Reservation Stations。 what is waiting for it? 2022/8/17 24 Tomasulo Example Cycle 8 I ns tr uc ti on s tat us : E xec W r i t eIns t ruc t i on j k Is s u e Co m p R es u l t Bu s y A d d res sLD F6 34+ R2 1 3 4 L oa d1 NoLD F2 45+ R3 2 4 5 L oa d2 NoM U L T D F0 F2 F4 3 L oa d3 NoS U BD F8 F6 F2 4 7 8D IV D F 10 F0 F6 5ADDD F6 F8 F2 6R e s e r v ati on Stat ions : S1 S2 RS RST i m e Nam e Busy Op Vj Vk Qj QkA dd1 No2 A dd2 Y e s ADDD (M M ) M (A 2)A dd3 No7 M ul t 1 Y e s M U L T D M (A 2) R(F 4)M ul t 2 Y e s D IV D M (A 1) M ul t 1R e gis te r r e s ult s tat us :C loc k F0 F2 F4 F6 F8 F 10 F 12 ... F 308 FU M ul t 1 M (A 2) A dd2 (M M ) M ul t 22022/8/17 25 Tomasulo Example Cycle 9 I ns tr uc ti on s tat us : E xec W r i t eIns t ruc t i on j k Is s u e Co m p R es u l t Bu s y A d d res sLD F6 34+ R2 1 3 4 L oa d1 NoLD F2 45+ R3 2 4 5 L oa d2 NoM U L T D F0 F2 F4 3 L oa d3 NoS U BD F8 F6 F2 4 7 8D IV D F 10 F0 F6 5ADDD F6 F8 F2 6R e s e r v ati on Stat ions : S1 S2 RS RST i m e Nam e Busy Op Vj Vk Qj QkA dd1 No1 A dd2 Y e s ADDD (M M ) M (A 2)A dd3 No6 M ul t
規(guī)章制度相關(guān)推薦
鄂ICP備17016276號(hào)-1