Spilltempo

Spilltempo is a metric used in computer systems and performance engineering to quantify the cadence of memory spill events from fast caches to slower memory during workload execution. A spill occurs when data residing in a fast cache (such as L1 or L2) cannot be kept in that cache due to capacity or associativity limits and must be moved to a lower level of the memory hierarchy. Spilltempo describes the timing and frequency of such events, offering a temporal view of memory pressure beyond traditional miss rates.

The term originated in memory hierarchy analysis and performance benchmarking discussions in the mid-2010s, gaining traction as developers sought time-based measures of memory pressure.

Spilltempo can be expressed as spills per second, or as the mean inter-spill interval within profiling windows. Profilers can approximate by recording spill events along with timestamps; hardware performance counters may expose cache eviction counters in some architectures that can be used to approximate spills.

Applications include guiding cache-conscious data structures and memory-allocation strategies, informing compiler optimizations, and serving as a diagnostic measure in performance benchmarking. Interpreting spilltempo requires context; a high value may indicate poor data locality or insufficient cache capacity, but bursts of spills can occur without degrading overall performance depending on workload and hardware. Related topics include cache miss rate, cache hierarchy, memory bandwidth.