Re: gettimeofday nanoseconds patch (makes it possible for theposix-timer functions to return higher accuracy)

From: john stultz
Date: Wed Jul 14 2004 - 19:54:00 EST


On Wed, 2004-07-14 at 17:08, Christoph Lameter wrote:
> On Wed, 14 Jul 2004, john stultz wrote:
> > On Wed, 2004-07-14 at 13:28, Christoph Lameter wrote:
> > > > None the less, I do understand the desire for the change (and am working
> > > > to address it in 2.7), so could you at least use a better name then
> > > > gettimeofday()? Maybe get_ns_time() or something? Its just too similar
> > > > to do_gettimeofday and the syscall gettimeofday().
> > >
> > > Right. I had it named getnstimeofday before but the feeling was that the
> > > patch should not introduce a new name. Any approach that would allow
> > > progress on the issue would be fine with me.
> >
> > Fair enough. getnstimeofday() sounds good enough for me.
>
> Ok. A modified patch is following.

I guess it looks good enough for me. I'd say send it to Andrew when
you're ready.

George, do you have any additional comments?

Although you still have the issue w/ NTP adjustments being ignored, but
last time I looked at the time_interpolator code, it seemed it was being
ignored there too, so at least your not doing worse then the ia64
do_gettimeofday(). [If I'm doing the time_interpolator code a great
injustice with the above, someone please correct me]

> > > > Really, I feel the cleaner method is to fix do_gettimeofday() so it
> > > > returns a timespec and then convert it to a timeval in
> > > > sys_gettimeofday(). However this would add overhead to the syscall, so I
> > > > doubt folks would go for it.
> > >
> > > do_gettimeofday is used all over the linux kernel for a variety of
> > > purposes and lots of code depends on the presence of a timeval struct.
> >
> > Indeed, it would be a decent amount of work to clean that up as well.
>
> The cleanup can be done gradually after this patch is in. I volunteer
> to work on this (hoping that my employer may support that ;-) ).

I'll try to remember to cc you on the 2.7 code when I get the first pass
ready (re-implementing the NTP mechanism is the last blocker). I'm sure
to appreciate additional feedback from non i386 arch specific views.

thanks
-john

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