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

[Kay Sievers]

On Thu, Mar 10, 2011 at 01:25, Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx> wrote:
> On Wed, Â9 Mar 2011 16:36:51 +0200
> Alexander Shishkin <virtuoso@xxxxxxxxx> wrote:
>
>> Changes since v3:
>> Â- changed timerfd_settime() semantics (see below)
>> Changes since v2:
>> Â- replaced sysfs interface with a syscall
>> Â- added sysctl/procfs handle to set a limit to the number of users
>> Â- fixed issues pointed out by Greg.
>> Changes since v1:
>> Â- updated against 2.6.36-rc1,
>> Â- added notification/filtering options,
>> Â- 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. ÂI guess the most common
> application is the 1,001 desktop clock widgets. ÂDo 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.

Kay
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