When doing long term recording and waiting for some event to snapshot
on, we often only care about the last minute or so.

The --switch-output command line option supports rotating the perf.data
file when the size exceeds a threshold. But the disk would still be
filled with unnecessary old files.

Add a new option to only keep a number of rotated files, so that the
disk space usage can be limited.
Signed-off-by: Andi Kleen <ak@linux.intel.com>
Acked-by: Jiri Olsa <jolsa@kernel.org>
LPU-Reference: 20190314225002.30108-3-andi@firstfloor.org
Link: https://lkml.kernel.org/n/tip-y5u2lik0ragt4vlktz6qc9ks@git.kernel.orgSigned-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>