Re: relatime: update once per day patches (was: ext3 IO latency measurements)

Andrew Morton
2009-03-26T16:34:18Z

On Thu, 26 Mar 2009 09:14:28 -0700 (PDT) Linus Torvalds <torvalds@linux-foundation.org> wrote:

>
>
> On Thu, 26 Mar 2009, Andrew Morton wrote:
> >
> > Hard-wiring a 24-hour interval into the core VFS for all mounted
> > filesystems is dumb.
>
> Umm.
>
> I generally agree witht he "leave policy to user space" people, but this
> is an area where (a) user space has shown itself to not get it right (ie
> people don't do even the existing relatime because distros don't) and (b)
> what's the alternative?
>
> > I (and others) pointed out that it would be better to implement this as
> > a mount option. That suggestion was met with varying sillinesses and
> > that is where things stand.
>
> I'd suggest first just doing the 24 hour thing, and then, IF user space
> actually ever gets its act together, and people care, and they _ask_ for a
> mount option, that's when it's worth doing.
>

We wouldn't normally just enable the new feature by default because it
changes kernel behaviour. Userspace needs to be changed in some manner to
opt-in. One way it's `mount -o remount', the other way it's a poke in
/proc.