While "inotify" is specific to the linux kernel, it is widespread enough that it's worth mentioning some of the effect it has on tail -f:
>From acbfebeb8d22a87b76fae32d8d9bf0473e178fdf Mon Sep 17 00:00:00 2001 From: Jim Meyering <meyer...@redhat.com> Date: Mon, 23 May 2011 16:09:42 +0200 Subject: [PATCH 1/2] doc: describe how kernel inotify support affects tail -f * doc/coreutils.texi (tail invocation) [-f]: Mention how inotify kernel support makes a difference. Prompted by http://bugzilla.redhat.com/662900 --- doc/coreutils.texi | 5 +++++ 1 files changed, 5 insertions(+), 0 deletions(-) diff --git a/doc/coreutils.texi b/doc/coreutils.texi index 289c0ba..dfaf4c9 100644 --- a/doc/coreutils.texi +++ b/doc/coreutils.texi @@ -2830,6 +2830,11 @@ tail invocation Likewise, the @option{-f} option has no effect for any operand specified as @samp{-}, when standard input is a FIFO or a pipe. +With kernel inotify support, output is asynchronous and generally very prompt. +Otherwise, @command{tail} sleeps for one second between checks--- +use @option{--sleep-interval=@var{N}} to change that default---which can +make the output appear slightly less responsive or bursty. + @item -F @opindex -F This option is the same as @option{--follow=name --retry}. That is, tail -- 1.7.5.2.1.g56b30