is not stable on network filesystems. With `USE_NSEC`
compile-time option, `st_mtim.tv_nsec` and `st_ctim.tv_nsec`
members are also compared, but this is not enabled by default
-because the value of this member becomes meaningless once the
-inode is evicted from the inode cache on filesystems that do not
-store it on disk.
-
+because in-core timestamps can have finer granularity than
+on-disk timestamps, resulting in meaningless changes when an
+inode is evicted from the inode cache. See commit 8ce13b0
+of git://git.kernel.org/pub/scm/linux/kernel/git/tglx/history.git
+([PATCH] Sync in core time granuality with filesystems,
+2005-01-04).
Racy git
--------