From ae6683d815895c2be1e60e1942630fa99488055b Mon Sep 17 00:00:00 2001 From: Sebastian Andrzej Siewior Date: Fri, 26 Jul 2019 20:30:51 +0200 Subject: [PATCH] hrtimer: Introduce HARD expiry mode On PREEMPT_RT not all hrtimers can be expired in hard interrupt context even if that is perfectly fine on a PREEMPT_RT=n kernel, e.g. because they take regular spinlocks. Also for latency reasons PREEMPT_RT tries to defer most hrtimers' expiry into soft interrupt context. But there are hrtimers which must be expired in hard interrupt context even when PREEMPT_RT is enabled: - hrtimers which must expiry in hard interrupt context, e.g. scheduler, perf, watchdog related hrtimers - latency critical hrtimers, e.g. nanosleep, ..., kvm lapic timer Add a new mode flag HRTIMER_MODE_HARD which allows to mark these timers so PREEMPT_RT will not move them into softirq expiry mode. [ tglx: Split out of a larger combo patch. Added changelog ] Signed-off-by: Sebastian Andrzej Siewior Signed-off-by: Thomas Gleixner Acked-by: Peter Zijlstra (Intel) Link: https://lkml.kernel.org/r/20190726185752.981398465@linutronix.de --- include/linux/hrtimer.h | 6 ++++++ 1 file changed, 6 insertions(+) diff --git a/include/linux/hrtimer.h b/include/linux/hrtimer.h index 24072a0..15c2ba6 100644 --- a/include/linux/hrtimer.h +++ b/include/linux/hrtimer.h @@ -38,6 +38,7 @@ enum hrtimer_mode { HRTIMER_MODE_REL = 0x01, HRTIMER_MODE_PINNED = 0x02, HRTIMER_MODE_SOFT = 0x04, + HRTIMER_MODE_HARD = 0x08, HRTIMER_MODE_ABS_PINNED = HRTIMER_MODE_ABS | HRTIMER_MODE_PINNED, HRTIMER_MODE_REL_PINNED = HRTIMER_MODE_REL | HRTIMER_MODE_PINNED, @@ -48,6 +49,11 @@ enum hrtimer_mode { HRTIMER_MODE_ABS_PINNED_SOFT = HRTIMER_MODE_ABS_PINNED | HRTIMER_MODE_SOFT, HRTIMER_MODE_REL_PINNED_SOFT = HRTIMER_MODE_REL_PINNED | HRTIMER_MODE_SOFT, + HRTIMER_MODE_ABS_HARD = HRTIMER_MODE_ABS | HRTIMER_MODE_HARD, + HRTIMER_MODE_REL_HARD = HRTIMER_MODE_REL | HRTIMER_MODE_HARD, + + HRTIMER_MODE_ABS_PINNED_HARD = HRTIMER_MODE_ABS_PINNED | HRTIMER_MODE_HARD, + HRTIMER_MODE_REL_PINNED_HARD = HRTIMER_MODE_REL_PINNED | HRTIMER_MODE_HARD, }; /* -- 2.7.4