Re: Caching

[tb@MIT.EDU (Thomas Bushnell, BSG)]

Brent Fulgham <bfulgham@xpsystems.com> writes:

> For instance, while editing files in vim, I notice that each
> keystroke I make (while writing -- not just moving the cursor)
> is mirrored by a "tick" noise from my hard disk (i.e., a write
> action is occuring).

I'm not sure exactly why a disk I/O needs to be happening on each such
read; basically:

each character is a completed read call
each completed read call means the atime must be updated
the filesystem ends up getting a file_utimes call on the terminal's
  "underlying node" which holds the atime information for the tty

but hurd/libdiskfs/file-utimes.c does not do any sync at all, so
there's no reason disk I/O should get queued for any of this.  (Though
it is still dirty, and the next time the filesystem gets synced you
will certainly see a disk I/O.)

What are the options to your root filesystem?  Do `fsysopts /' and
maybe we can see something odd.

Thomas