Man pages matching name perf_event_open in section 2:

perf_event_open.2.en	debian 10 / manpages-dev
perf_event_open.2.en	debian 11 / manpages-dev
perf_event_open.2.fr	debian 11 / manpages-fr-dev
perf_event_open.2.en	debian 12 / manpages-dev
perf_event_open.2.fr	debian 12 / manpages-fr-dev
perf_event_open.2.ru	debian 12 / manpages-ru-dev