Re: [PATCH 1/7] notify userspace about time changes

[Alan Cox]

> Certain userspace applications (like "clock" desktop applets or cron) might
> want to be notified when some other application changes the system time. It
> might also be important for an application to be able to distinguish between
> its own and somebody else's time changes.

A program that cannot work out if it or someone else changed the time is
very very broken indeed !

> This patch implements a notification interface via eventfd mechanism. Proccess
> wishing to be notified about time changes should create an eventfd and pass it
> to time_change_notify() syscall along with notification options.

This seems complete overkill and it doesn't really help applications much
that I can see because of suspend/resume.

What are your actual use cases ?

Clocks apps don't care because they check the actual time so notice it
shfited. Cron and anacron appear to contain the needed internal handling.

Anything sleeping until a time occurs maybe ? In which case its a lot
simpler and cleaner than events to provide a new itimer which wakes the
process when the wall time hits the time specified in the timer.

Alan
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