Performance Management in the Virtual Data Center: an Assessment

摘要

1. Impact of virtualized clocks and timers guest machine % Processor Time counters are distorted The Windows clock interrupt that drives CPU usage sampling is impacted Correction factor for CPU Usage measurement at the Process/Thread level 2. Difference counters that report a rate/sec can be impacted, although the events are still being counted correctly 3. Timestamps gathered using the rdtsc instruction are virtualied Guest OS sees "apparent time" such that successive invocations of rdtsc return monotonically increasing values e.g., the Windows counters that report Disk latency 4. Instantaneous counters remain valid sampled observations.