Messages in this thread | | | Date | Tue, 16 Mar 2021 13:21:29 +0100 | From | Peter Zijlstra <> | Subject | Re: [PATCH 01/10] tick/nohz: Prevent tick_nohz_get_sleep_length() from returning negative value |
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On Thu, Mar 11, 2021 at 01:36:59PM +0100, Frederic Weisbecker wrote: > From: "Zhou Ti (x2019cwm)" <x2019cwm@stfx.ca> > > If the hardware clock happens to fire its interrupts late, two possible > issues can happen while calling tick_nohz_get_sleep_length(). Either: > > 1) The next clockevent device event is due past the last idle entry time. > > or: > > 2) The last timekeeping update happened before the last idle entry time > and the next timer callback expires before the last idle entry time. > > Make sure that both cases are handled to avoid returning a negative > duration to the cpuidle governors.
Why? ... and wouldn't it be cheaper the fix the caller to check negative once, instead of adding two branches here?
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