Re: itimer again (Re: [PATCH] RTC: Add mmap method to rtc character driver)

Nicholas Miell
2006-07-29T23:36:03Z

On Sat, 2006-07-29 at 15:51 -0700, Bill Huey wrote:
> On Sat, Jul 29, 2006 at 11:49:48PM +0200, Edgar Toernig wrote:
> > Bill Huey (hui) wrote:
> > > Well, this points out a serious problem with doing an mmap extension to
> > > /dev/rtc. It would be better to have a page mapped by another device like
> > > /dev/jiffy_counter, or something like that rather than to overload the
> > > /dev/rtc with that functionality.
> >
> > You mean something like this, /dev/itimer?
> >
> > http://marc.theaimsgroup.com/?m=115412412427996
>
> [CCing Steve and Ingo on this thread]
>
> It's a different topic than what Keith needs, but this is useful for another
> set of purposes. It's something that's really useful in the RT patch since
> there isn't a decent API to get at high resolution timers in userspace. What
> you've written is something that I articulated to Steve Rostedt over a dinner
> at OLS and is badly needed in the -rt patches IMO. I suggest targeting that
> for some kind of inclusion to Ingo Molnar's patchset.
>

Do you mind summarizing what's wrong with the existing interfaces for
those of us who didn't have the opportunity to join you for dinner at
OLS?

--
Nicholas Miell <nmiell@comcast.net>