> And on Linux inotify is bound by /proc/sys/fs/inotify/max_user_watches. Six of one, half dozen the other. FreeBSD file descriptor limit is arbitrary and can be raised to INT_MAX (2 billion). That should be plenty.
Yes, on Linux you're limited to max_user_watches, and you can edit that value, just like you say with kqueue... but you need root access, so for end user applications this is not really a solution.
With inotify i use one watch per-folder, with kqueue you need to do it by file ( of course you can watch the folder changes, but you need to keep a copy of the file states in that folder, and then re-stat that files to find out what file was changed, not even close to an ideal solution ). So for example in my use case with inotify i can watch 65536 folders, and with kqueue less than 10000 files ( that could be a single folder! ).
Edit:
It seems that FreeBSD default a much bigger number for FDs ( https://news.ycombinator.com/item?id=9063893 ), so that should suffice a lot of use cases, that's good news for me!
> With inotify i use one watch per-folder, with kqueue you need to do it by file ( of course you can watch the folder changes, but you need to keep a copy of the file states in that folder, and then re-stat that files to find out what file was changed, not even close to an ideal solution ). So for example in my use case with inotify i can watch 65536 folders, and with kqueue less than 10000 files ( that could be a single folder! ).
Ah, I looked at inotify API briefly and did not notice that directory watches return file changes. That does make it easier to use than kevent vnode watches. Mea culpa.
Yes, on Linux you're limited to max_user_watches, and you can edit that value, just like you say with kqueue... but you need root access, so for end user applications this is not really a solution. With inotify i use one watch per-folder, with kqueue you need to do it by file ( of course you can watch the folder changes, but you need to keep a copy of the file states in that folder, and then re-stat that files to find out what file was changed, not even close to an ideal solution ). So for example in my use case with inotify i can watch 65536 folders, and with kqueue less than 10000 files ( that could be a single folder! ).
Edit: It seems that FreeBSD default a much bigger number for FDs ( https://news.ycombinator.com/item?id=9063893 ), so that should suffice a lot of use cases, that's good news for me!