[OT] Re: [PATCH 86/87] fs: switch timespec64 fields in inode to discrete integers

Gabriel Paubert
2023-10-01T05:39:26Z

On Sat, Sep 30, 2023 at 09:50:41AM -0500, Steve French wrote:
> On Fri, Sep 29, 2023 at 3:06 AM David Howells via samba-technical
> <samba-technical@lists.samba.org> wrote:
> >
> >
> > Jeff Layton <jlayton@kernel.org> wrote:
> >
> > > Correct. We'd lose some fidelity in currently stored timestamps, but as
> > > Linus and Ted pointed out, anything below ~100ns granularity is
> > > effectively just noise, as that's the floor overhead for calling into
> > > the kernel. It's hard to argue that any application needs that sort of
> > > timestamp resolution, at least with contemporary hardware.
> >
> > Albeit with the danger of making Steve French very happy;-), would it make
> > sense to switch internally to Microsoft-style 64-bit timestamps with their
> > 100ns granularity?
>
> 100ns granularity does seem to make sense and IIRC was used by various
> DCE standards in the 90s and 2000s (not just used for SMB2/SMB3 protocol and
> various Windows filesystems)

Historically it probably comes from VMS, where system time and file
timestamps were a 64 bit integer counting in 100ns units starting on MJD
2400000.5 (Nov 17th 1858).

Gabriel

>
>
> --
> Thanks,
>
> Steve