Pipelining

Which one of the following dependencies among the register operands of different instructions can cause a data hazard in a pipelined processor?

The EX stage of a pipelined processor performs the memory read operations for LOAD instructions, and the operations for the arithmetic and logic instructions. Let $t_{E X}$ denote the time taken by the EX stage to perfor...

A non-pipelined instruction execution unit that operates at 1.6 GHz clock takes an average of 5 clock cycles to complete the execution of an instruction. To improve the performance, the system was pipelined with a goal o...

A 5-stage instruction pipeline has stage delays of $180,250,150,170$, and 250 , respectively, in nanoseconds. The delay of an inter-stage latch is 10 nanoseconds. Assume that there are no pipeline stalls due to branches...

A non-pipelined instruction execution unit operating at 2 GHz takes an average of 6 cycles to execute an instruction of a program P. The unit is then redesigned to operate on a 5-stage pipeline at 2 GHz. Assume that the...

The baseline execution time of a program on a 2 GHz single core machine is 100 nanoseconds ( ns ). The code corresponding to 90% of the execution time can be fully parallelized. The overhead for using an additional core...

Consider a 5-stage pipelined processor with Instruction Fetch (IF), Instruction Decode (ID), Execute (EX), Memory Access (MEM), and Register Writeback (WB) stages. Which of the following statements about forwarding is/ar...

An instruction format has the following structure: Instruction Number: Opcode destination reg, source reg-1, source reg-2 Consider the following sequence of instructions to be executed in a pipelined processor: I1: DIV R...

Consider a 3-stage pipelined processor having a delay of 10 ns (nanoseconds), 20 ns, and 14 ns, for the first, second, and the third stages, respectively. Assume that there is no other delay and the processor does not su...

A processor X 1 operating at 2 GHz has a standard 5-stage RISC instruction pipeline having a base CPI (cycles per instruction) of one without any pipeline hazards. For a given program P that has 30% branch instructions,...

Consider a pipelined processor with 5 stages, Instruction Fetch (IF), Instruction Decode (ID), Execute (EX), Memory Access (MEM), and Write Back (WB). Each stage of the pipeline, except the EX stage, takes one cycle. Ass...

A five-stage pipeline has stage delays of 150, 120, 150, 160 and 140 nanoseconds. The registers that are used between the pipeline stages have a delay of 5 nanoseconds each. The total time to execute 100 independent inst...

Consider a non-pipelined processor operating at 2.5 GHz. It takes 5 clock cycles to complete an instruction. You are going to make a 5-stage pipeline out of this processor. Overheads associated with pipelining force you...

The instruction pipeline of a $$RISC$$ processor has the following stages: Instruction Fetch $$(IF),$$ Instruction Decode $$(ID),$$ Operand Fetch $$(OF),$$ Perform Operation $$(PO)$$ and Writeback $$(WB).$$ The $$IF,$$ $...

The stage delays in a $$4$$-stage pipeline are $$800, 500, 400$$ and $$300$$ picoseconds. The first stage (with delay $$800$$ picoseconds) is replaced with a functionally equivalent design involving two stages with respe...

Consider a $$3$$ $$GHz$$ (gigahertz) processor with a three-stage pipeline and stage latencies $${\tau _1},{\tau _2},$$ and $${\tau _3}$$ such that $${\tau _1} = 3{\tau _2}/4 = 2{\tau _3}.$$ If the longest pipeline stage...

Suppose the functions $$F$$ and $$G$$ can be computed in $$5$$ and $$3$$ nanoseconds by functional units $${U_F}$$ and $${U_G},$$ respectively. Given two instances of $${U_F}$$ and two instances of $${U_G},$$ it is requi...

Consider the sequence of machine instructions given below: MUL R5, R0, R1 DIV R6, R2, R3 ADD R7, R5, R6 SUB R8, R7, R4 In the above sequence, $$R0$$ to $$R8$$ are general purpose registers. In the instructions shown, the...

Consider a non-pipelined processor with a clock rate of 2.5 gigahertz and average cycles per instruction of four. The same processor is upgraded to a pipelined processor with five stages; but due to the internal pipeline...

Consider the following code sequence having five instructions $${I_1}$$ to $${I_5}$$. Each of these instructions has the following format. $$\,\,\,\,\,\,\,\,\,\,\,\,\,\,OP\,\,Ri,\,\,Rj,\,\,Rk$$ where operation $$OP$$ is...

Consider the following processors ($$ns$$ stands for nanoseconds). Assume that the pipeline registers have zero latency. $$P1:$$ Four-stage pipeline with stage latencies $$1$$ $$ns,$$ $$2$$ $$ns,$$ $$2$$ $$ns,$$ $$1$$ $$...

An instruction pipeline has five stages, namely, instruction fetch $$(IF),$$ instruction decode and register fetch $$(ID/RF)$$ instruction execution $$(EX),$$ memory access $$(MEM),$$ and register writeback $$(WB)$$ with...

Consider a $$6$$-stage instruction pipeline, where all stages are perfectly balanced. Assume that there is no cycle-time overhead of pipelining. When an application is executing on this $$6$$-stage pipeline, the speedup...

Consider an instruction pipeline with five stages without any branch prediction: Fetch Instruction $$(FI),$$ Decode Instruction $$(DI),$$ Fetch Operand $$(FO),$$ Execute Instruction $$(EI)$$ and Write Operand $$(WO).$$ T...

Register renaming is done in pipelined processors

For all delayed conditional branch instructions, irrespective of whether the condition evaluate true or false,

In an instruction execution pipeline, the earliest that the data $$TLB$$ (Translation Look aside Buffer) can be accessed is

Which of the following are NOT true in a pipelined processor? $$1.$$ Bypassing can handle all RAW hazards $$2.$$ Register renaming can eliminate all register carried WAR hazards $$3.$$ Control hazard penalties can be eli...

The following code is to run on a pipelined processor with one branch delay slot $$\eqalign{ & {{\rm I}_1}:\,\,ADD\,\,{R_2}\,\, \leftarrow \,\,{R_7} + {R_8} \cr & {{\rm I}_2}:\,\,SUB\,\,\,{R_4}\,\, \leftarrow \,\,{R_5} -...

A CPU has five stages pipeline and runs at $$1$$ $$GHz$$ frequency. Instruction fetch happens in the first stage of the pipeline. A conditional branch instruction computes the target address and evaluates the condition i...

A $$4$$-stage pipeline has the stage delays as $$150, 120,160$$ and $$140$$ nano seconds respectively. Registers that are used between the stages have a delay of $$5$$ nanoseconds each. Assuming constant clocking rate, t...

For a pipelined $$CPU$$ with a single $$ALU$$, consider the following situations $$1.\,\,\,\,\,$$ The $$j+1$$ instruction uses the result of the $$j$$-$$th$$ instruction as an operand $$2.\,\,\,\,\,$$ The execution of a...

The performance of a pipelined processor suffers if

Comparing the time $$T1$$ taken for a single instruction on a pipelined $$CPU$$ with time $$T2$$ taken on a non-pipelined but identical $$CPU,$$ we can say that

An instruction pipeline has five stages where each stage takes $$2$$ nanoseconds and all instructions use all five stages. Branch instructions are not overlapped, i.e., the instruction after the branch is not fetched til...