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authorThomas Gleixner <[email protected]>2023-06-15 11:18:30 +0200
committerThomas Gleixner <[email protected]>2023-06-16 20:45:28 +0200
commit13bb06f8dd42071cb9a49f6e21099eea05d4b856 (patch)
tree0601f36ced15ca75bd8d0199f964974991ab1c9d /tools/perf/scripts/python/intel-pt-events.py
parent858fd168a95c5b9669aac8db6c14a9aeab446375 (diff)
tick/common: Align tick period during sched_timer setup
The tick period is aligned very early while the first clock_event_device is registered. At that point the system runs in periodic mode and switches later to one-shot mode if possible. The next wake-up event is programmed based on the aligned value (tick_next_period) but the delta value, that is used to program the clock_event_device, is computed based on ktime_get(). With the subtracted offset, the device fires earlier than the exact time frame. With a large enough offset the system programs the timer for the next wake-up and the remaining time left is too small to make any boot progress. The system hangs. Move the alignment later to the setup of tick_sched timer. At this point the system switches to oneshot mode and a high resolution clocksource is available. At this point it is safe to align tick_next_period because ktime_get() will now return accurate (not jiffies based) time. [bigeasy: Patch description + testing]. Fixes: e9523a0d81899 ("tick/common: Align tick period with the HZ tick.") Reported-by: Mathias Krause <[email protected]> Reported-by: "Bhatnagar, Rishabh" <[email protected]> Suggested-by: Mathias Krause <[email protected]> Signed-off-by: Thomas Gleixner <[email protected]> Signed-off-by: Sebastian Andrzej Siewior <[email protected]> Signed-off-by: Thomas Gleixner <[email protected]> Tested-by: Richard W.M. Jones <[email protected]> Tested-by: Mathias Krause <[email protected]> Acked-by: SeongJae Park <[email protected]> Cc: [email protected] Link: https://lore.kernel.org/[email protected] Link: https://lore.kernel.org/[email protected] Link: https://lore.kernel.org/r/[email protected]
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