It's clear to me that perf always records one or more events, and the sampling can be counter-based or time-based. But when the -e and -F switches are not given, what is the default behavior of perf record? The manpage for perf-record doesn't tell you what it does in this case.
The default event is cycles, as can be seen by running perf script after perf record. There, you can also see that the default sampling behavior is time-based, since the number of cycles is not constant. The default frequency is 4000 Hz, which can be seen in the source code and checked by comparing the file size or number of samples to a recording where -F 4000 was specified.
The perf wiki says that the rate is 1000 Hz, but this is not true anymore for kernels newer than 3.4.