Which are often needed to evaluate the cache performance?

Answer: Hit Ratio is the primary metric often needed to evaluate cache performance.

• Hit Ratio — definition and formula:

  • Hit ratio = hits / (hits + misses).

  • Why it matters: a higher hit ratio means more requests are served from the cache, reducing access to slower storage and improving efficiency.

• Other related metrics and tools:

  • Latency: measures time to service a request. Useful to quantify user-perceived performance and to see the impact of cache hits versus misses.

  • Transfer Rate (throughput): measures amount of data transferred per time unit. It complements hit ratio when evaluating system throughput and bandwidth effects.

  • Cache Traces: logs of memory or request accesses used for workload analysis, simulation, and diagnosing low hit ratios or suboptimal policies.

Summary: Hit ratio is often the key metric used to evaluate cache effectiveness. Latency and transfer rate are important complementary performance metrics, and cache traces are analysis tools to understand and improve cache behavior.