Man pages matching name catalyst::plugin::cache::backend::fastmmap in section 3pm:

Catalyst::Plugin::Cache::Backend::FastMmap.3pm.en	debian 10 / libcatalyst-plugin-cache-store-fastmmap-perl
Catalyst::Plugin::Cache::Backend::FastMmap.3pm.en	debian 11 / libcatalyst-plugin-cache-store-fastmmap-perl
Catalyst::Plugin::Cache::Backend::FastMmap.3pm.en	debian 12 / libcatalyst-plugin-cache-store-fastmmap-perl