• Ingo Molnar's avatar
    [PATCH] i386: improve sched_clock() on i686 · f9690982
    Ingo Molnar authored
    Clean up sched_clock() on i686: it will use the TSC if available and falls
    back to jiffies only if the user asked for it to be disabled via notsc or
    the CPU calibration code didnt figure out the right cpu_khz.
    
    This generally makes the scheduler timestamps more finegrained, on all
    hardware.  (the current scheduler is pretty resistant against asynchronous
    sched_clock() values on different CPUs, it will allow at most up to a jiffy
    of jitter.)
    
    Also simplify sched_clock()'s check for TSC availability: propagate the
    desire and ability to use the TSC into the tsc_disable flag, previously
    this flag only indicated whether the notsc option was passed.  This makes
    the rare low-res sched_clock() codepath a single branch off a read-mostly
    flag.
    Signed-off-by: default avatarIngo Molnar <mingo@elte.hu>
    Signed-off-by: default avatarAndrew Morton <akpm@osdl.org>
    Signed-off-by: default avatarAndi Kleen <ak@suse.de>
    f9690982
tsc.c 10.7 KB