Re: [PATCHv6 0/7] system time changes notification

From: Davide Libenzi
Date: Thu Nov 11 2010 - 21:37:43 EST


On Thu, 11 Nov 2010, Thomas Gleixner wrote:

> > [...]
> >
> > This would also enable the folks who want to support things like PHY
> > hardware clocks (for very-low-latency ethernet timestamping). It
> > would resolve the enumeration problem; instead of 0, 1, 2, ... as
> > constants, they would show up in sysfs and be open()able. Ideally you
> > would be able to set up ntpd to slew the "realtime" clock by following
> > a particular hardware clock, or vice versa.
>
> There are other plans for the various interesting clocks floating
> around which look pretty good.
>
> But what you folks really want for this stuff is an extension to
> timerfd as you want to be able to poll, right?
>
> So what about the following:
>
> Add a new flag TDF_NOTIFY_CLOCK_WAS_SET to the timerfd flags. Now this
> flag adds the timer to a separate list, which gets woken up when the
> clock is set.

What chu talkin bout Willis? :)
This borders the interface multiplexing, if I got your idea correctly.
Timerfd is about expiring private timers, not about getting out
notifications about system-wide time changes.
I understand your concerns about that code, but please do not use timerfd
as a sacrificial mule to fit something which IMO does not belong there.



- Davide


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