• john stultz's avatar
    Cache xtime every call to update_wall_time · 17c38b74
    john stultz authored
    This avoids xtime lag seen with dynticks, because while 'xtime' itself
    is still not updated often, we keep a 'xtime_cache' variable around that
    contains the approximate real-time that _is_ updated each time we do a
    'update_wall_time()', and is thus never off by more than one tick.
    
    IOW, this restores the original semantics for 'xtime' users, as long as
    you use the proper abstraction functions (ie 'current_kernel_time()' or
    'get_seconds()' depending on whether you want a timespec or just the
    seconds field).
    
    [ Updated Patch.  As penance for my sins I've also yanked another #ifdef
      that was added to avoid the xtime lag w/ hrtimers.  ]
    Signed-off-by: default avatarJohn Stultz <johnstul@us.ibm.com>
    Cc: Ingo Molnar <mingo@elte.hu>
    Cc: Thomas Gleixner <tglx@linutronix.de>
    Signed-off-by: default avatarLinus Torvalds <torvalds@linux-foundation.org>
    17c38b74
hrtimer.c 35.2 KB