The speedup on \( p \) processors can be greater than \( p \) if memory usage is optimal! Consider the case of a memorybound computation with \( M \) words of memory

• If \( M/p \) fits into cache while \( M \) does not, the time to access memory will be different in the two cases:
• \( T_1 \) uses the main memory bandwidth
• \( T_p \) uses the appropriate cache bandwidth