On Thu, 10 Mar 2011, Kay Sievers wrote: > 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. Note, that we have CLOCK_BOOTTIME pending for .39 which aims at the same problem. It's basically CLOCK_MONOTONIC adjusted by the time we were in suspend. So while CLOCK_MONOTONIC timers are not aware of the time spent in suspend CLOCK_BOOTTIME timers are. The reason for implementing CLOCK_BOOTTIME was basically the same problem. Thanks, tglx
