Subject: bug#18958: 25.0.50; auto-revert-mode reacts slowly even if using an event-driven backend

From: Dima Kogan <[email-masked]>
Date: Sun, 22 Feb 2015 19:47:35 -0800

Michael Albinus <[email-masked]> writes:

> Dima Kogan <[email-masked]> writes:
>
>> In a perfect world, this 1-second delay would be removed upstream, and
>> we'd use gfilenotify for everything. In the meantime, is gfilenotify
>> better in any way on Linux? If the notifications are unavailable for
>> some reason (network-mounted file for instance), then emacs simply
>> decays to the normal polled notifications, right?
>
> You mean auto-revert, right? And yes, if `file-notify-add-watch' doesn't
> return a proper watch descriptor, auto-revert falls back to its polling
> mode.

Yes, I meant auto-revert.

> glib is said to use also polling for file systems where you don't have
> native file notification support. This would make it superior to inotify
> for mounted filesystems, and alike.

But how is it superior? Didn't you just say that when inotify fails then
emacs polls, just as would happen with gfilenotify? To confirm, I just
used an inotify-configured emacs to auto-revert on a file mounted on a
network samba mount. As expected, the auto-revert-mode does work, but in
a polled instead of event-driven fashion. So unless I'm missing
something, then when you run the current emacs code on Linux both
inotify and gfile work the same way EXCEPT gfile always has a 1-second
notification delay while inotify does not. I'm probably missing
something.