Lec13a - COMP 4300 Computer Architecture Scoreboard An...

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1 COMP 4300 Computer Architecture Scoreboard - An Example Dr. Xiao Qin Auburn University http://www.eng.auburn.edu/~xqin xqin@auburn.edu Fall, 2010
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2 Scoreboard Example Cycle 1 Instruction status  Read ExecutioWrite Instruction j k Issue operandscompleteResult LD F6 34+ R2 1 LD F2 45+ R3 MULTDF0 F2 F4 SUBD F8 F6 F2 DIVD F10 F0 F6 ADDD F6 F8 F2 Functional unit status dest S1 S2 FU for j FU for k Fj? Fk? Time Name Busy Op Fi Fj Fk Qj Qk Rj Rk Integer Yes Load F6 R2 Yes Mult1 No Mult2 No Add No Divide No Register result status Clock F0 F2 F4 F6 F8 F10 F12 ... F30 1 FU Integer Issue LD #1 Shows in which cycle the operation occurred.
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3 Scoreboard Example Cycle 2 Instruction status  Read ExecutioWrite Instruction j k Issue operand completeResult LD F6 34+ R2 1 2 LD F2 45+ R3 MULTDF0 F2 F4 SUBD F8 F6 F2 DIVD F10 F0 F6 ADDD F6 F8 F2 Functional unit status dest S1 S2 FU for j FU for k Fj? Fk? Time Name Busy Op Fi Fj Fk Qj Qk Rj Rk Integer Yes Load F6 R2 Yes Mult1 No Mult2 No Add No Divide No Register result status Clock F0 F2 F4 F6 F8 F10 F12 ... F30 2 FU Integer LD #2 can’t issue since ? integer unit is busy. MULT can’t issue because we require in-order issue.
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4 Scoreboard Example Cycle 3 Instruction status  Read ExecutioWrite Instruction j k Issue operand completeResult LD F6 34+ R2 1 2 3 LD F2 45+ R3 MULTDF0 F2 F4 SUBD F8 F6 F2 DIVD F10 F0 F6 ADDD F6 F8 F2 Functional unit status dest S1 S2 FU for j FU for k Fj? Fk? Time Name Busy Op Fi Fj Fk Qj Qk Rj Rk Integer Yes Load F6 R2 Yes Mult1 No Mult2 No Add No Divide No Register result status Clock F0 F2 F4 F6 F8 F10 F12 ... F30 3 FU Integer
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5 Scoreboard Example Cycle 4 Instruction status  Read ExecutioWrite Instruction j k Issue operand completeResult LD F6 34+ R2 1 2 3 4 LD F2 45+ R3 MULTDF0 F2 F4 SUBD F8 F6 F2 DIVD F10 F0 F6 ADDD F6 F8 F2 Functional unit status dest S1 S2 FU for j FU for k Fj? Fk? Time Name Busy Op Fi Fj Fk Qj Qk Rj Rk Integer Yes Load F6 R2 Yes Mult1 No Mult2 No Add No Divide No Register result status Clock F0 F2 F4 F6 F8 F10 F12 ... F30 4 FU Integer
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6 Scoreboard Example Cycle 5 Instruction status  Read ExecutioWrite Instruction j k Issue operand completeResult LD F6 34+ R2 1 2 3 4 LD F2 45+ R3 5 MULTDF0 F2 F4 SUBD F8 F6 F2 DIVD F10 F0 F6 ADDD F6 F8 F2 Functional unit status dest S1 S2 FU for j FU for k Fj? Fk? Time Name Busy Op Fi Fj Fk Qj Qk Rj Rk Integer Yes Load F2 R3 Yes Mult1 No Mult2 No Add No Divide No Register result status Clock F0 F2 F4 F6 F8 F10 F12 ... F30 5 FU Integer Issue LD #2 since integer unit is now free.
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7 Scoreboard Example Cycle 6 Instruction status  Read ExecutioWrite Instruction j k Issue operand completeResult LD F6 34+ R2 1 2 3 4 LD F2 45+ R3 5 6 MULT F0 F2 F4 6 SUBD F8 F6 F2 DIVD F10 F0 F6 ADDD F6 F8 F2 Functional unit status dest S1 S2 FU for j FU for k Fj? Fk? Time Name
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Lec13a - COMP 4300 Computer Architecture Scoreboard An...

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