Hi Peter, On 2/15/09, Peter Zijlstra <a.p.zijlstra@xxxxxxxxx> wrote: > On Thu, 2009-02-12 at 08:17 +1300, Michael Kerrisk wrote: >> Hi Peter, >> >> Peter Zijlstra wrote: >> > On Tue, 2009-02-10 at 14:54 +1300, Michael Kerrisk wrote: >> >> If the value of the CLOCK_REALTIME clock is adjusted while an >> >> absolute timer based on that clock is armed, then the expira- >> >> tion of the timer will be appropriately adjusted. Adjustments >> >> to the CLOCK_REALTIME clock have no effect on relative timers >> >> based on that clock. >> > >> > I cannot find this to be true. >> > >> >>From what I can make of the code, clock_settime() ends up calling >> > do_sys_settimeofday() for CLOCK_REALTIME (and the other clocks). >> > >> > It is, however, not treating relative/abs timers any differently. >> > >> > Both get converted to an absolute expiration time when set. >> > >> > If POSIX mandates that we keep relative timers unchanged when we change >> > the underlying clock, we'd have to iterate all pending timers and reset >> > them. >> >> The rules do indeed come from POSIX. >> >> And indeed the rules do seem to be followed on Linux. Since I found >> parts of the code to be hard to track, I also checked things with an >> example program. (Ahhh! the pitfalls of reading code to find the >> truth!) > > Ah, quite so. The magic is in hrtimers. Relative timers are ran on clock > monotonic. > > OK I think that was the last bit. > > Feel free to add: > > Reviewed-by: Peter Zijlstra <a.p.zijlstra@xxxxxxxxx> > > To all 4 pathces. Done. Thanks for looking the pages over. Cheers, Michael -- Michael Kerrisk Linux man-pages maintainer; http://www.kernel.org/doc/man-pages/ git://git.kernel.org/pub/scm/docs/man-pages/man-pages.git man-pages online: http://www.kernel.org/doc/man-pages/online_pages.html Found a bug? http://www.kernel.org/doc/man-pages/reporting_bugs.html -- To unsubscribe from this list: send the line "unsubscribe linux-man" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
