divetime

Divetime is a term used in computer performance analysis to describe the amount of time a program spends performing division operations. It is typically reported as part of microarchitectural profiling results, alongside metrics such as instruction counts, cache misses, and branch predictions. The concept applies to both integer division and floating-point division, with the two often exhibiting different latencies and throughputs on modern CPUs.

Divetime can be expressed in wall time (seconds or nanoseconds), CPU time (core time), or as a share of total runtime or as cycles. Profiling tools may separate it by instruction type or by divisor value to identify hotspots where division is a dominant cost. Because division generally has higher latency than many other arithmetic operations, high divetime often points to performance bottlenecks in numerical loops, data processing, and graphics pipelines.

Optimization strategies to reduce divetime include replacing divisions by multiplications by reciprocals when the divisor is constant, precomputing division results, restructuring algorithms to perform divisions less frequently, and using bit-shift or alternative arithmetic when appropriate. In floating-point contexts, using fused multiply-add or reciprocal approximations can yield speedups with acceptable accuracy trade-offs.

Limitations: divetime is a hardware- and compiler-dependent metric. The absolute value of divetime can vary across architectures and compiler optimizations; it does not capture time spent on downstream effects of division, such as memory access or control flow. It should be used in conjunction with a broader profiling view to guide optimization.