The patch titled sched_clock: widen the max and min time has been removed from the -mm tree. Its filename was sched_clock-widen-the-max-and-min-time.patch This patch was dropped because it was merged into mainline or a subsystem tree The current -mm tree may be found at http://userweb.kernel.org/~akpm/mmotm/ ------------------------------------------------------ Subject: sched_clock: widen the max and min time From: Steven Rostedt <rostedt@xxxxxxxxxxx> With keeping the max and min sched time within one jiffy of the gtod clock was too tight. Just before a schedule tick the max could easily be hit, as well as just after a schedule_tick the min could be hit. This caused the clock to jump around by a jiffy. This patch widens the minimum to last gtod + (delta_jiffies ? delta_jiffies - 1 : 0) * TICK_NSECS and the maximum to last gtod + (2 + delta_jiffies) * TICK_NSECS This keeps the minum to gtod or if one jiffy less than delta jiffies and the maxim 2 jiffies ahead of gtod. This may cause unstable TSCs to be a bit more sporadic, but it helps keep a clock with a stable TSC working well. Signed-off-by: Steven Rostedt <srostedt@xxxxxxxxxx> Cc: Peter Zijlstra <peterz@xxxxxxxxxxxxx> Cc: Ingo Molnar <mingo@xxxxxxx> Cc: Thomas Gleixner <tglx@xxxxxxxxxxxxx> Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx> --- kernel/sched_clock.c | 11 +++++++++-- 1 file changed, 9 insertions(+), 2 deletions(-) diff -puN kernel/sched_clock.c~sched_clock-widen-the-max-and-min-time kernel/sched_clock.c --- a/kernel/sched_clock.c~sched_clock-widen-the-max-and-min-time +++ a/kernel/sched_clock.c @@ -96,14 +96,21 @@ static void __update_sched_clock(struct s64 delta = now - scd->prev_raw; WARN_ON_ONCE(!irqs_disabled()); - min_clock = scd->tick_gtod + delta_jiffies * TICK_NSEC; + + min_clock = scd->tick_gtod + + (delta_jiffies ? delta_jiffies - 1 : 0) * TICK_NSEC; if (unlikely(delta < 0)) { clock++; goto out; } - max_clock = min_clock + TICK_NSEC; + /* + * The clock must stay within a jiffie of the gtod. + * But since we may be at the start of a jiffy or the end of one + * we add another jiffy buffer. + */ + max_clock = scd->tick_gtod + (2 + delta_jiffies) * TICK_NSEC; if (unlikely(clock + delta > max_clock)) { if (clock < max_clock) _ Patches currently in -mm which might be from rostedt@xxxxxxxxxxx are linux-next.patch ftrace-disable-function-tracing-bringing-up-new-cpu.patch split-the-typecheck-macros-out-of-include-linux-kernelh.patch locking-add-typecheck-on-irqsave-and-friends-for-correct-flags.patch locking-add-typecheck-on-irqsave-and-friends-for-correct-flags-fix.patch -- To unsubscribe from this list: send the line "unsubscribe mm-commits" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html