Re: [RFCv4] timerfd: add TFD_NOTIFY_CLOCK_SET to watch for clock changes

[Alexander Shishkin <virtuoso@slind.org>]

On Thu, Mar 10, 2011 at 01:36:18AM +0100, Kay Sievers wrote:
> On Thu, Mar 10, 2011 at 01:25, Andrew Morton <akpm@linux-foundation.org> wrote:
> > On Wed,  9 Mar 2011 16:36:51 +0200
> > Alexander Shishkin <virtuoso@slind.org> wrote:
> >
> >> Changes since v3:
> >>  - changed timerfd_settime() semantics (see below)
> >> Changes since v2:
> >>  - replaced sysfs interface with a syscall
> >>  - added sysctl/procfs handle to set a limit to the number of users
> >>  - fixed issues pointed out by Greg.
> >> Changes since v1:
> >>  - updated against 2.6.36-rc1,
> >>  - added notification/filtering options,
> >>  - added Documentation/ABI/sysfs-kernel-time-notify interface description.
> 
> > It would be helpful to know if the identified users of this feature
> > actually find it useful and adequate.  I guess the most common
> > application is the 1,001 desktop clock widgets.  Do you have any
> > feedback from any of the owners of those?
> 
> We want it for systemd, to provide cron-like functionality but without
> the need to stupidly wake up every minute and check the system time
> for possible jumps.
> 
> It also sounds useful for a generic resume (after system suspend)
> notification for applications, which isn't really possible today.

Yes, but with John's CLOCK_BOOTTIME patches (which are in the tip tree
currently) it will be.

Regards,
--
Alex