CS 470/570 Lecture 4

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# CS 470/570 Lecture 4 - PowerPoint PPT Presentation

CS 470/570 Lecture 4. Performance measures Interconnection networks Cache coherence Parallel Software Parallel Program design Example Problems. Performance Measures. Speedup T serial /T parallel Efficiency Speedup/number of processors Amdahl’s law Scalable. Interconnection Networks.

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Presentation Transcript
CS 470/570 Lecture 4
• Performance measures
• Interconnection networks
• Cache coherence
• Parallel Software
• Parallel Program design
• Example Problems
Performance Measures
• Speedup
• Tserial/Tparallel
• Efficiency
• Speedup/number of processors
• Amdahl’s law
• Scalable
Interconnection Networks
• Bus
• Crossbar
• Fully connected
• Hypercube
• Omega
• Latency
• Bandwidth
Cache Coherence
• Snooping cache coherence
• Directory based cache coherence
Parallel Software
• Nondeterminism
• Race conditions
• Critical section
• Mutual exclusion
Parallel Program Design
• Partitioning
• Communication
• Aggregation
Example Problems
• 1. Draw a 4X4 crossbar switch.
• 2. Draw a 4X4 Omega network
• 3. Suppose there are 16 processors connected in a 4 dimensional hypercube.
• a. How many direct connections to other processors does each processor have?
• b. What is the minimum number of links that will have to be traversed to send data from processor 3 to processor 12?
Example Problems
• 4. Suppose you have a machine with 4 cores that uses snooping cache coherence. Core 0 reads from address 10,000, core 3 reads from address 10,000. Core 3 writes to address 10,000. How does Core 0 know its copy of the contents of address 10,000 is out of date.
• 5. On a 4X4 Omega network can the following source destination requests be satisfied at the same time. (0,0), (3,1), (1,2), (2,3)
• 6. How many switches are in an 8X8 crossbar?
• 7. How many switches are on an 8X8 Omega network?