004-pipelining - Pipelining Principles of pipelining Simple...

Info iconThis preview shows pages 1–10. Sign up to view the full content.

View Full Document Right Arrow Icon
ECE D52 Lecture Notes: Chapter 3 1 © 1998 by Hill, Wood, Sohi, Smith and Vijaykumar and Moshovos Pipelining • Principles of pipelining • Simple pipelining • Structural Hazards • Data Hazards • Control Hazards • Interrupts • Multicycle operations • Pipeline clocking
Background image of page 1

Info iconThis preview has intentionally blurred sections. Sign up to view the full version.

View Full DocumentRight Arrow Icon
ECE D52 Lecture Notes: Chapter 3 2 © 1998 by Hill, Wood, Sohi, Smith and Vijaykumar and Moshovos Sequential Execution Semantics We will be studying techniques that exploit the semantics of Sequential Execution. Sequential Execution Semantics: instructions appear as if they executed in the program specified order and one after the other Alternatively At any given point in time we should be able to identify an instruction so that: 1. All preceding instructions have executed 2. None following has executed
Background image of page 2
ECE D52 Lecture Notes: Chapter 3 3 © 1998 by Hill, Wood, Sohi, Smith and Vijaykumar and Moshovos Exploiting Sequential Semantics • The “it should appear” is the key • The only way one can inspect execution order is via the machine’s state This includes registers, memory and any other named storage We will looking at techniques that relax execution order while preserving sequential execution semantics
Background image of page 3

Info iconThis preview has intentionally blurred sections. Sign up to view the full version.

View Full DocumentRight Arrow Icon
ECE D52 Lecture Notes: Chapter 3 4 © 1998 by Hill, Wood, Sohi, Smith and Vijaykumar and Moshovos Steps of Instruction Execution Fetch Decode Read Operands Operation Writeback Result Determine Next Instruction Instruction execution is not a monolithic action There are multiple micro- actions involved
Background image of page 4
ECE D52 Lecture Notes: Chapter 3 5 © 1998 by Hill, Wood, Sohi, Smith and Vijaykumar and Moshovos Pipelining: Partially Overlap Instructions Ideally : This ignores fill and drain times Time pipeline sequential PipelineDepth ------------------------------------------ = Unpipelined instructions time 1/Throughput latency Pipelined instructions time 1/Throughput latency
Background image of page 5

Info iconThis preview has intentionally blurred sections. Sign up to view the full version.

View Full DocumentRight Arrow Icon
ECE D52 Lecture Notes: Chapter 3 6 © 1998 by Hill, Wood, Sohi, Smith and Vijaykumar and Moshovos Sequential Semantics Preserved? Two execution states: 1. In-progress: changes not visible to outsiders 2. Committed: changes visible fetch I4 decode I4 r0 = r0 + r2 fetch I5 decode I5 r1 = r1 + 1 fetch I6 decode I6 r3 = r1 != 10 Time a b committed in-progress in-progress
Background image of page 6
ECE D52 Lecture Notes: Chapter 3 7 © 1998 by Hill, Wood, Sohi, Smith and Vijaykumar and Moshovos Principles of Pipelining: Example Critical Path Determines Clock Cycle Overlap Pick Longest Stage
Background image of page 7

Info iconThis preview has intentionally blurred sections. Sign up to view the full version.

View Full DocumentRight Arrow Icon
ECE D52 Lecture Notes: Chapter 3 8 © 1998 by Hill, Wood, Sohi, Smith and Vijaykumar and Moshovos Principles of Pipelining: Ideal Case Let T be the time to execute an instruction Instruction execution requires n stages, t 1 ...t n taking T = W/O pipelining: W/ n-stage pipeline: If all t i are equal, Speedup is n Ideally: Want higher Performance? Use more pipeline stages t i TR 1 T --- 1 t i ----- == Latency T 1 -------- 1 max t i () ------------------ n T = n i × T = Speedup t i i n =
Background image of page 8
ECE D52 Lecture Notes: Chapter 3 9 © 1998 by Hill, Wood, Sohi, Smith and Vijaykumar and Moshovos Pipelining Limits • After a certain number of stages benefits level off and later they start diminishing • Pipeline Utility is limited by: 1. Implementation
Background image of page 9

Info iconThis preview has intentionally blurred sections. Sign up to view the full version.

View Full DocumentRight Arrow Icon
Image of page 10
This is the end of the preview. Sign up to access the rest of the document.

Page1 / 80

004-pipelining - Pipelining Principles of pipelining Simple...

This preview shows document pages 1 - 10. Sign up to view the full document.

View Full Document Right Arrow Icon
Ask a homework question - tutors are online