Re: ext4 features

Trond Myklebust
2006-07-05T19:34:10Z

On Wed, 2006-07-05 at 08:59 -0400, J. Bruce Fields wrote:
> On Wed, Jul 05, 2006 at 08:24:29AM -0400, Bill Davidsen wrote:
> > Theodore Tso wrote:
> > >Some of the ideas which have been tossed about include:
> > >
> > > * nanosecond timestamps, and support for time beyond the 2038
> >
> > The 2nd one is probably more urgent than the first. I can see a general
> > benefit from timestamp in ms, beyond that seems to be a specialty
> > requirement best provided at the application level rather than the bits
> > of a trillion inodes which need no such thing.
>
> What's urgently needed for NFS (and I suspect for most other
> applications demanding higher timestamps) isn't really nanosecond
> precision so much as something that's guaranteed to increase whenever
> the file changes.

NFS doesn't necessarily require monotonicity either. The only real
requirement that knfsd has is that the timestamp needs to change every
time the file data (mtime+ctime) and/or metadata (ctime only) is
changed.

Applications like 'make' OTOH, probably would be happier if the
timestamps are guaranteed to be monotonic.

Cheers,
Trond