When configuring profiling session, you may choose between two types of time measurement: based on OS performance counters and based on CPU register values. In the latter case, to calculate method execution time, dotTrace takes time values from a CPU core register called Time Stamp Counter (TSC). Typically, on multi-core processors, TSCs of all cores are synced with each other. Nevertheless, on some types of Intel CPUs these counters may be mistimed. As a result, dotTrace can get wrong time values in case application threads are switched between CPU cores during profiling. For example, method execution time may be smaller than the time of underlying methods.
Snapshots with such issues are considered invalid.