On Thu, Sep 27, 2018 at 11:41:49PM +0200, Thomas Gleixner wrote: > On Thu, 27 Sep 2018, Thomas Gleixner wrote: > > Add time skew via NTP/PTP into the picture and you might have to adjust > > timers as well, because you need to guarantee that they are not expiring > > early. > > > > I haven't looked through Dimitry's patches yet, but I don't see how this > > can work at all without introducing subtle issues all over the place. > > And just a quick scan tells me that this is broken. Timers will expire > early or late. The latter is acceptible to some extent, but larger delays > might come with surprise. Expiring early is an absolute nono. Do you mean that we have to adjust all timers after changing offset for CLOCK_MONOTONIC or CLOCK_BOOTTIME? Our idea is that offsets for monotonic and boot times will be set immediately after creating a time namespace before using any timers. It is interesting to think what a use-case for changing these offsets after creating timers. It may be useful for testing needs. A user sets a timer in an hour and then change a clock offset forward and check that a test application handles the timer properly. > > Thanks, > > tglx >
