perf.data file has no samples

Question

I am using perf 3.0.4 on ubuntu 11.10. Its record command works well and displays on terminal 256 samples collected. But when I make use of perf report , it giv

Answer 1

Whenever I run into this on a machine where perf record has worked in the past, it is because I have left something else running that uses the performance counters, e.g., I have perf top running in another terminal tab.

In this case, it seems that perf record simply doesn't record any PMU related samples.