Re: explicit dcache <-> user-space cache coherency, sys_mark_dir_clean(), O_CLEAN

Ingo Molnar
2004-02-23T16:45:24Z

* Jamie Lokier <jamie@shareable.org> wrote:

> Another issue is that most machines don't have nanosecond resolution
> clocks (e.g. m68k is limited to timer interrupt resolution, and some
> x86 machines cannot use the cycle counter), [...]

this is not an issue, with the monotonicity solution i suggested: if
prev_time == curr_time then curr_time.tv_nsec++.

> [...] and most filesystems don't store them either.

their problem. There's at least one filesystem that does it right (XFS),
the rest will be handled via natural selection.

> The right place to put the delay is in the kernel, when mtime is set
> or when it is read, or both.

no need to delay anything - just do the tv_nsec++ thing!

Ingo