Hardware Reference
In-Depth Information
2. Branch stalls —Two-cycle stalls on every taken branch plus unfilled or canceled branch
delay slots
3. FP result stalls —Stalls because of RAW hazards for an FP operand
4. FP structural stalls —Delays because of issue restrictions arising from conflicts for function-
al units in the FP pipeline
Figure C.52 shows the pipeline CPI breakdown for the R4000 pipeline for the 10 SPEC92
benchmarks. Figure C.53 shows the same data but in tabular form.
FIGURE C.52 The pipeline CPI for 10 of the SPEC92 benchmarks, assuming a perfect
cache . The pipeline CPI varies from 1.2 to 2.8. The leftmost five programs are integer pro-
grams, and branch delays are the major CPI contributor for these. The rightmost five pro-
grams are FP, and FP result stalls are the major contributor for these. Figure C.53 shows the
numbers used to construct this plot.
 
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