proxy_cache_revalidate seems to prevent the cache manager to remove inactive cache objects

[teodorescuserban@…]

My config:

http {
...
proxy_cache_path /srv/cache/nginx_cache levels=1:2 keys_zone=cache:128m max_size=2048m inactive=10m;
...
server {
location / {
...
proxy_cache_valid 200 1m;
proxy_cache_use_stale error timeout updating http_500 http_502 http_503 http_504;
proxy_cache_lock on;
proxy_cache_background_update on;
proxy_cache_revalidate on;
...
}
...
}
...
}

Everything working as expected, but no files are removed from the disk cache.
The backend is not actually capable of honouring the revalidate mechanism just yet but I added it in there to be ready when needed.

Since I clearly remembered that the cache manager does actually remove the old, inactive files for other sites, I fiddled with the config enough times to conclude that the proxy_cache_revalidate option is the one stopping the removal of the old inactive cache objects.

My issue is that I could not find:

1. how often the cache manager goes trough the files to remove the old inactive objects (or clear up some space if min_free or max_size are used)
2. any link in any documentation between proxy_cache_revalidate and the cache manager process.

The technical issue is solved, but I would appreciate a pointer to a documentation to explain this better.

Thank you!