CS 452/652 Fall 2019 - Lecture 10

September 25, 2019 prev next

Timing Measurements (cont'd)

  • measure as:
    start := clock;
    loop N times:
    stop := clock;
  • compute average time and/or enhanced statistics
  • potential overheads
  • N must be large enough to mitigate impact of these overheads
  • experiment duration?

    ARM 920T CPU Caches

    ARM 920T Cache Setup

  • setup information in co-processor register p15
  • accessed via MCR/MRC instructions
    MCR{<cond>} p15, 0, <Rd>, <CRn>, <CRm>{, <opcode2>}
    MRC{<cond>} p15, 0, <Rd>, <CRn>, <CRm>{, <opcode2>}
  • <CRn> set to c1 for cache enable/disable
  • <CRn> set to c7 for cache operations
  • necessary operations